Chemistry of Matter Properties and Interactions of Elements MS State Objectives 2.a. and 2.b.

Matter Anything that has mass and takes up space (volume) Examples: A brick has mass and takes up space A desk has mass and takes up space A pencil has mass and takes up space Air has mass and takes up space All of the above examples are considered matter because they have mass and take up space. Can you think of anything that would not be considered matter?

Atoms Smallest possible unit into which matter can be divided, while still maintaining its properties. Made up of: protons neutrons electrons The solar system is commonly used as an analogy to describe the structure of an atom - + For example, what is the smallest possible unit into which a long essay can be divided and still have some meaning? - + + - + + - -

Protons (+) + Positively charged particles Help make up the nucleus of the atom Help identify the atom (could be considered an atom’s DNA) Equal to the atomic number of the atom Contribute to the atomic mass Equal to the number of electrons + - +

Neutrons Neutral particles; have no electric charge + - Neutral particles; have no electric charge Help make up the nucleus of the atom Contribute to the atomic mass

Electrons (-) - - + Negatively charged particles Found outside the nucleus of the atom, in the electron orbits/levels; each orbit/level can hold a maximum number of electrons ( 1st = 2, 2nd = 8, 3rd = 8 or 18, etc…) Move so rapidly around the nucleus that they create an electron cloud Mass is insignificant when compared to protons and neutrons Equal to the number of protons Involved in the formation of chemical bonds + - -

Hydrogen (H) Atom - Notice the one electron in the first orbital = 1 + = 0 - How many more electrons can fit in the 1st orbital/ level? + Even though there are no neutrons present, Hydrogen is still considered an atom

Oxygen (O) Atom Notice the two electrons in the first orbital/level and the six in the second + - = 8 How many more electrons can fit in the 2nd orbital/ level? - - - + + + + - - + + - - -

Sodium (Na) Atom Notice the two electrons in the first orbital/level, eight in the second, and one in the third + - = 11 = 12 - - - How many more electrons can fit in the 3rd orbital/ level? - + + + + - - - + + - - - -

Practice MR. JONES

Notice that the electrons are not apart of the nucleus The Atom’s “Center” Protons and neutrons are grouped together to form the “center” or nucleus of an atom. Notice that the electrons are not apart of the nucleus + - - -

QUARKS + Particles that make up protons and neutrons Notice the smaller particles that make up this neutron after you take a closer look. Notice the smaller particles that make up this proton after you take a closer look. + What do you notice about the number of quarks in the neutron and proton?

Sub-Atomic Particles Weight Comparison (protons, neutrons, electrons) Neutron = 1.6749286 x10-27 kg Proton = 1.6726231 x10-27 kg Electron = 9.1093897 x10-31 kg - - + 1839 electrons = 1 neutron 1836 electrons = 1 proton + How do you think the mass of a neutron compares to that of a proton? 1 neutron ≈ 1 proton

What would be the atomic number of this atom? The number of protons in the nucleus of an atom - What would be the atomic number of this atom? + - -

Mass Number + + What would be the mass number of this atom? - - - The total number of protons and neutrons in an atom’s nucleus Expressed in Atomic Mass Units (amu) Each proton or neutron has a mass of 1 amu What would be the mass number of this atom? - +  3  4 + - 3 protons + 4 neutrons = a mass number of 7 amu Why did we not account for the electrons when calculating the mass number? -

Building Atoms Atoms Protons Neutrons Electrons Carbon 6 Beryllium 4 5 Using the whiteboard and the proton, neutron, and electron pieces, build the following atoms, and determine their atomic and mass numbers. Atoms Protons Neutrons Electrons Carbon 6 Beryllium 4 5 Oxygen 8 Lithium 3 Sodium 11 12

http://www.pbs.org/wgbh/aso/try it/atom/ Atom Builder Using the interactive website link below, practice building atoms. http://www.pbs.org/wgbh/aso/try it/atom/ Using the classzone.com link below, click on the “Build an Atom” simulation and practice building atoms. http://www.classzone.com/books/ml_sci_physical/page_build.cfm?id=resour_ch1&u=2##

Elements Elements are substances that cannot be broken down into simpler substances. Made up of only one type of atom Basic building blocks of matter The smallest particle of an element is an atom.

Atomic Structure Two main parts: The nucleus is a small space at the center of an atom which contains protons and neutrons Atomic number is the proton number Atomic mass = the nucleus = protons + neutrons The electron cloud is the area surrounding the nucleus which contains electrons arranged in energy levels Made mostly of empty space and almost massless electrons Electrons are arranged in energy levels and travel in random paths around the nucleus The number of electrons equals the number of protons in a neutral atom

Developing the Periodic table Dmitri Mendeleev, a Russian scientist discovered a set of patterns that seemed to apply to all elements arranged the elements in order of increasing atomic mass (protons + neutrons in the nucleus)

Modern Periodic Table In 1913, Henry Moseley discovered a way to measure the positive charge in the nucleus to determine the atomic number arranged the elements by increasing atomic number instead of atomic mass

Periodic Table Arranged by increasing atomic number (proton #) Rows are called periods & are labeled 1-7 There are 18 columns Each tall column contains a group or family of elements. Groups are elements that have similar physical or chemical properties. Ex. All elements in group 1 are metals & react violently with water.

Element A pure substance made up of one kind of atom that cannot be broken down into simpler substances by physical or chemical means 90 occur naturally on earth 25 were synthesized (made) by scientists

Periodic  Periodic Law  Periodic Table Something periodic occurs at regular or at least generally predictable intervals Periodic law - physical and chemical properties of the elements are periodic functions of their atomic numbers Periodic Table of Elements – a table of the elements, arranged by atomic number, that shows the patterns in their properties; based on the periodic law Can you think of anything that is periodic?

Groups and Periods

Groups/Families Groups 1 and 2 along with Groups 13 and 18 are called the representative elements. -elements having similar properties.

Groups/Families Groups 3 to 12 are called the transition metals.

How many groups (families) FROM TOP TO BOTTOM OR BOTTOM TO THE TOP Important Features of the Periodic Table: Group (Family) each column of elements on the periodic table How many groups (families) are on the Periodic Table Of Elements? FROM TOP TO BOTTOM OR BOTTOM TO THE TOP

Atoms with Few Electrons in their Outer Energy Level 11 Na 22.990 Notice: only 1 electron in outer level + - + - 4 Be 9.012 Notice: only 2 electrons in outer level

Atoms with Full or Almost Full Outer Energy Level + - 8 O 15.999     + - Notice: 2 electrons in outer level – FULL 2 He 4.003 + - Notice: 6 electrons in outer level – almost full Notice: 7 electrons in outer level – almost full 9 F 18.998

Atoms with ½ (≈) Complete Outer Energy Level + - Notice: only 4 electrons in outer level                     5 B 10.811 + - Notice: only 3 electrons in outer level 14 Si 28.086

Examples of Group Elements with the same # of valence electrons                            How many electrons do each of these atoms have in their outer orbital/level? 87 Fr (223) 55 Cs 132.905 37 Rb 85.468 19 K 39.098 11 Na 22.990 3 Li 6.941 1 H 1.008 + - What group (family) do these elements reside in?

Types of Elements Metals Nonmetals Metalloids

Metals & Non-metals Metals make up the majority of elements Non-metals Found on the left side of the periodic table in groups 1-15 ex. Copper (Cu) Non metals are found on the right side of the periodic table Ex. Carbon (C) Non-metals Found on the right side of the periodic table

Metalloids Found along a stair-step pattern between the metals & non-metals beginning in group 13 Ex. Silicon (Si) Also known as semi-metals

Group (Family) Names Alkali Metals Alkaline Earth Metals Noble Gases Boron Group Carbon Group Nitrogen Group Oxygen Group Halogens Transition Metals

Using the Periodic Table The boxes that make up the periodic table contain a significant amount of information. To understand this information, it is necessary to refer to the periodic table’s key(s) 8 O Oxygen 15.999 Atomic Number (Number of protons) Element Symbol (Written with a capital letter or a capital followed by a lower case if two letters ) Element Name Atomic Mass (Rounded to a whole number, equals the number of protons and neutrons) Class Color Metal Non-Metal Metalloid State (@ Room Temp.) Symbol Color Solid Liquid Gas What is Oxygen’s physical state of matter? Which class does Oxygen fall into?

Chemical Bond A force of attraction that holds two atoms together Has a significant effect on chemical and physical properties of compounds involves the valence electrons Valence Electrons – the electrons in the outermost energy level of an atom This Lithium Atom has one valence electron

Counting Valence Electrons Carbon 4 valence electrons Beryllium 2 valence electrons Oxygen 6 valence electrons

Examples of Period (Row) elements having the same number of orbitals/levels in their atoms + - + - In what period (row) do you think these atoms reside? + - + - In what period (row) do you think these atoms reside?

Examples of Group Elements with the same # of valence electrons                            How many electrons do each of these atoms have in their outer orbital/level? 87 Fr (223) 55 Cs 132.905 37 Rb 85.468 19 K 39.098 11 Na 22.990 3 Li 6.941 1 H 1.008 + - What group (family) do these elements reside in?

Identify the Element Period 5 – Group 2  Group 4 – Period 7  Rutherfordium - Rf Strontium - Sr Carbon - C Astatine - At

Neutron Calculations = 16 (P + N) – 8 (P) = 8 N How to Obtain the Number of Sub-Atomic Particles in an Atom Using a Periodic Table - - - 8 + + - = 8 + + O + - - + + Oxygen 15.9994 - - - Protons Neutrons Electrons + - Equal to the atomic # on the Periodic Table Equal to the atomic mass (rounded to a whole #) minus the # of protons Equal to the # of protons Example: Determine the # of protons, neutrons, and electrons in an atom of oxygen. Protons = 8 (Atomic #) Neutrons = 8 (Rounded atomic mass minus atomic #) Electrons = 8 (# of P) Neutron Calculations = 16 (P + N) – 8 (P) = 8 N

How to Obtain the Number of Sub-Atomic Particles in an Ion Using a Periodic Table 2- Notice how two electrons have been gained by the atom, thus resulting in an ion + + - = 8 + - + O + - + + 10 - - - Neutrons Protons Electrons + - Equal to the # of protons plus the # in the upper right corner if followed by a (-) OR minus the # in the upper right corner if followed by a (+) Equal to the atomic mass (rounded to a whole #) minus the # of protons Equal to the atomic # on the Periodic Table - Example: Determine the # of protons, neutrons, and electrons in the oxygen ion O²¯. Protons = 8 (Atomic #) Neutrons = 8 (Rounded atomic mass minus atomic #) Electrons = 10 Neutron Calculations = 16 (P + N) – 8 (P) = 8 N Electron Calculations = 8 (e) + 2 (e) = 10 -

Review How many protons does this element have? How many electrons does this element have? What is the atomic mass? How many neutrons does this atom have? What is the atomic number? Can you tell which element this is using any of this information? Explain.

How Elements Interact State Objective 2.a.

Physical Properties of Matter any property of matter that can be observed or measured without changing the identity of the matter Examples color shape taste state/phase density D = m V

Chemical Properties of Matter any property of matter that describes a substance based on its ability to change into a new substance Examples flammability reactivity with vinegar reactivity with oxygen Iron + Oxygen  Iron oxide (rust) 4Fe + 3O2  2Fe2O3

Chemical or Physical Property? Paper is white 2. Boiling point of H2O is 100oC Zinc reacts with hydrochloric acid and creates hydrogen gas Nitrogen does not burn Sulfur smells like rotten eggs Physical Property Physical Property Chemical Property Chemical Property Physical Property

Physical vs. Chemical Change Physical change occurs when the physical properties are changed, such as size or shape. Ex. Folding a piece of paper or a change in the state of matter: solid, liquid, gas Chemical change occurs when the chemical properties of the substance cause a change producing a new substance (the atoms have rearranged)

Examples of Chemical Reactions Food spoiling Combustion (fast Oxidation) Rusting (slow oxidation) Photosynthesis Respiration Tarnishing Food Cooking

Interaction Between Elements: If there are 110+ elements, how is it possible to have millions of different substances? Compounds are substances that form when two or more elements combine from a chemical change. Ex. NaCl (Sodium Chloride) The properties of compounds are different from the properties of the elements that make up the compound A molecule is the smallest particle of a substance with the same properties of that substance. Ex. H2O (water) each molecule behaves like water, if the molecule is divided, Hydrogen and oxygen no longer behave like water

How do Elements Interact in Chemical Changes? Chemical properties of elements are determined by the number of electrons in the outer most energy level called valence electrons Valence electron number is determined by the group number for representative elements

Element Families have similar chemical properties Alkali Metals: Group 1; 1 valence electron Alkaline Earth Metals: Group 2; 2 valence electrons Halogens: Group 17; 7 valence electrons Noble Gases: Group 18; 8 valence electrons

Compounds are molecules but not all molecules are compounds Combining Atoms There are over one hundred different types of atoms and they oftentimes combine to make new substances known as molecules and compounds Molecule Results from the bonding of two or more atoms Compound A substance that contains two or more different elements (atoms) Example – Oxygen Gas (O2) Example – Water (H2 O) Compounds are molecules but not all molecules are compounds

Molecule, Compound, or Both? Nitrogen Cl2 Chlorine NO2 Nitrogen Dioxide CO2 Carbon Dioxide O2 Oxygen CH4 Methane H2 Hydrogen NO Nitric Oxide H2O Water

Comparing Atoms, Molecules, Compounds, and Elements What’s the matter? Element Compound (or molecule)

Use the periodic table to answer the questions. Practice Use the periodic table to answer the questions. How many valence electrons does sodium have? How many electrons are found in the electron cloud of an atom of chlorine? What is the group number for each of the atomic models below?

Chemical Bonds Elements bond to other elements to become stable by having a full valence shell. Most elements need 8 valence electrons to become stable Elements will become stable by losing, gaining, or sharing valence electrons Elements that lose electrons become positively charged ions. CATION! Elements that gain electrons become negatively charged ions. ANION! WHAT IS AN ION? Types of bonding: Ionic Covalent

Ionic Bonding Ionic bonding is when a strong attraction occurs between oppositely charged ions to hold them close together to become stable (like two magnets) Ion: an atom that no longer has a neutral charge because it has lost or gained an electron Typically between a metal & non-metal Ex. Na+Cl-

Ionic Bonding animation

Covalent Bonding Covalent bonds are chemical bonds that form from atoms that share valence electrons to become stable Occurs between two or more nonmetals Ex. H2 , Cl2 , H2O , C6H12O6

Covalent Bonding

Forming Acids & Bases State Correlation 2b Chemistry of Matter Forming Acids & Bases State Correlation 2b

Properties of Acids & Bases An acid is a compound that produces hydrogen ions in water (H+) The greater the concentration of H ions produced, the stronger the acid Tastes sour Reacts with non-metals Have a pH < 7 Turn blue litmus paper red Examples: HCl, H2SO4, HNO3

Properties of Acids & Bases A base is any compound that produces hydroxide ions (OH-) in water. The greater the concentration of OH- produced, the stronger the base. Taste bitter & feels slippery Reacts with metals Have a pH > 7 Turn red litmus paper blue Examples: NH3, NaOH, NaHCO3

pH Scale animation

Predicting Acids & Bases using the Periodic Table Acids form when hydrogen chemically combines with certain nonmetals. All halogens (group 17) form acids when combined with hydrogen Ex. Fluorine & hydrogen (HF)

Predicting Acids & Bases using the Periodic Table Bases form when a hydroxide ion (OH-) joins with a metal The metals in group 1 (alkali metals) and group 2 (alkaline earth metals) readily form bases with hydroxide ions EX. KOH EX. Ca(OH)2

Determining the Number of Valence Electrons by Using the Periodic Table *Atoms of elements in Groups 1 and 2 have the same number of valence electrons as their group number. *Atoms of elements in Group 3-12 do not have a general rule relating their valence electrons to their group number. However, they typically have between 1 or 2 valence electrons. *Atoms of elements in Groups 13-18 have 10 fewer valence electrons than their group number. (Exception - helium atoms have only 2 valence electrons, even though they are in group 18)

How Many Valence Electrons? Hydrogen Lead Xenon Sulfur Rubidium 1 Valence Electron 4 Valence Electrons 8 Valence Electrons 6 Valence Electrons 1 Valence Electron

CONSIDER EIGHT A HAPPY NUMBER FOR ATOMS! The Octet Rule Atoms will combine to form compounds in order to reach eight electrons in their outer energy level. Atoms with less than 4 electrons tend to lose electrons. Atoms with more than 4 electrons tend to gain electrons. Be aware that there are some exceptions! CONSIDER EIGHT A HAPPY NUMBER FOR ATOMS!

The Octet Rule In Action 6 7 Notice how this chlorine atom has seven valence electrons, one away from eight. It will try to gain one more according to the Octet Rule. 5 + - 4 1 1 2 3 Notice how the sodium atom has one valence electron. It is this electron that it will try to get rid of according to the Octet Rule. Where do you think Chlorine finds that one electron that it needs?

Lewis Structure (Electron Dot Diagram) a way of drawing the outer energy level electrons (valence) of an atom The symbol for the element surrounded by as many dots as there are electrons in its outer energy level (valence) Examples How many valence electrons do each of these atoms have?

What Would the Electron Dot Diagram Look Like? 1 Valence Electron 6 Valence Electrons H O How many valence electrons does each atom have? Ne Sr 8 Valence Electrons 2 Valence Electrons

Oxidation Number The charge that an atom would have if it lost or gained electrons; ionic charge Can be helpful in determining which atoms will interact or bond with each other Example: According to electron dot diagram for Magnesium, it has two valence electrons. Because Magnesium is “unhappy” with two, it will typically lose them. If this happens it will turn into a Magnesium ion. At this point it will have an oxidation number of +2. 2+ Mg

What Could the Oxidation Number Be? +1 or -1 because it can gain or lose one electron -2 because it will gain two electrons Ne Sr 0 because it will not gain or lose electrons +2 because it will lose two electrons

3 Types of Chemical Bonds Ionic Covalent Metallic What can you describe about each of these bonds just by looking at the name?

IONIC BONDS The force of attraction between oppositely charged ions. Occurs after a transfer or loss/gain of electrons Usually form between atoms of metals and atoms of non-metals Resulting compounds have a name that usually ends in –ide 1- 1+ Cl Na Which different groups or families of elements will most-likely interact to create these types of bonds? - Example - Sodium Chloride (NaCl)

COVALENT BOND H O H - - - - + - + + - - - - - A force that bonds two atoms together by a sharing of electrons Each pair of shared electrons creates a bond Usually occurs between atoms of non-metals H O H - - - - + - + + - - - - - Example – Water (H2O)

Types of Covalent Bonds Different covalent bond types share a different number of electrons Water (H2O) Carbon Dioxide (CO2) Nitrogen (N2) Single Bonds Share 2 Electrons Double Bonds Share 4 Electrons Triple Bonds Share 6 Electrons

how the electrons do not just stay with one ion Metallic Bond A force of attraction between a positively charged metal ion and the electrons in a metal Many metal ions pass along many electrons Many properties of metals, such as conductivity, ductility, and malleability, result from the freely moving electrons in the metal Usually occurs between atoms of metals Al3+ - - - Notice how the electrons do not just stay with one ion - - - - - - - - - - -

Results of Bonding Compound Molecule A neutral group of two or more non- metal atoms held together by covalent bonds Type: Diatomic - molecules consisting of two atoms of the same element bonded together Examples: H2, F2, O2, N2 Compound A pure substance composed of two or more different elements (atoms) that are chemically combined Examples: CO, NO2, NaCl What would you call something that has characteristics of both?

MAKE AT LEAST 3 DIFFERENT BONDS! Lets Bond On you note cards choose 3 DIFFERENT elements. Answer these two questions: What type of bond did you make? (Ionic, Covalent, or Metallic) Why did you bond?  MAKE AT LEAST 3 DIFFERENT BONDS!

Chemical Formulas Chemical formulas show a combination of chemical symbols & numbers that indicate which elements & how many atoms of each element are present in a compound. H2O (Water) C6H12O6 (Sugar/glucose) O2 (Oxygen Molecule) CO2 (Carbon Dioxide) N2 (Nitrogen Molecule) Subscript: # of atoms

Chemical Equations A process that produces a chemical change is called a chemical reaction. Reactants are substances that exist before the reaction begins Products are substances that form as a result of the reaction Chemical equations tell chemists the reactants, products, and proportions of each substance present in a reaction ( like a recipe) Ex. 2H2 + O2 2H2O Reactant Product

Hints For Balancing Equations Count the atoms List the number of atoms of each element to see which elements must be balanced Use a coefficient to add atoms to one side of the equation Start with the reactant or product that has the greatest number of different elements Add a coefficient to another reactant or product Make sure that the coefficients in your balanced equation are the smallest whole numbers possible (they should have no common factor other than one) Tutorial on Balancing Equations

Law of Conservation of Mass The Law of Conservation of Mass states that mass (matter) can neither be created nor destroyed. Therefore, atoms are never lost or created during a chemical reaction. Chemical equations must be balanced in order to show the same number of atoms for each element on the reactant & product side of the equation.

Law of Conservation of Mass Proposed by Antoine Lavoisier In a chemical reaction, atoms are neither created nor destroyed All atoms present in the reactants are also present in the products Chemical equations must account for/show the conservation of mass  balancing equations In its present form, does this chemical equation show a conservation of mass? 2 H2 + O2  2 H2O Reactants Products How would you balance this equation to show the conservation of mass? H  2 O  2 4 2 H  2 O  1 4 2

Balancing an Equation Ex. 2H2 + O2 2H2O Reactant Product