Atomic Theory and Bonding Chapter 4.1: Atomic Theory and Bonding Vocabulary: matter, mass, volume, substance, chemical change, physical change, state, particle, gas, liquid, solid, attract

Vocabulary: matter pure substance atom mixture Atomic theory nucleus molecule compound chemical change element property pure substance mixture nucleus proton neutron electron subatomic particle orbital shell valence shell

Chemistry is the study of... MATTER!!!

What is matter? Anything with mass and volume Found in 3 phases: liquid, solid, gas Cannot be created or destroyed, it only changes form

Atomic Theory John Dalton came up with the Atomic Theory (1800’s) Atomic Theory: Everything is made of tiny particles called atoms.

Atoms and Molecules: Atoms are the smallest part of an element Molecules are two or more atoms combined

ATOMS FORM COMPOUNDS Atoms join together to form compounds. A compound is composed of two or more different atoms combined in a specific way. Ex: Oxygen and hydrogen are atoms/elements; H2O is a compound.

ATOMS FORM COMPOUNDS

CHEMICAL CHANGE A chemical change occurs when the arrangement of atoms in compounds changes to form new compounds.

CHEMICAL CHANGE Sodium Na (solid) Chlorine Cl (gas) Salt NaCl

Vocabulary Definition Atom The smallest particle of an element that still has the properties of the element Element A pure substance that cannot be broken down into simpler materials. Contains only one kind of atom Compound A pure substance that has more than two types of elements bonded chemically together ex: H2O, CH4, H2SO4

A pure substance made of two or more atoms joined together Molecule A pure substance made of two or more atoms joined together ex: H2O, CH4, H2SO4, H2, N2, Cl2 Property Something that is used to tell one substance apart from another ex: colour, density, melting point… Pure substance Has identical properties in every sample (elements and compounds) Mixture Two or more substances put together but not chemically combined Can have different properties for different samples

The Atom: An atom is the smallest part of an element The nucleus is the center of the atom Most of the mass of an atom is in the nucleus nucleus

The Atom: The nucleus is composed of -positive protons -neutral neutrons Protons have a positive charge Neutrons have no charge (they are neutral)

ATOMIC THEORY Because protons have a + charge, the nucleus always has a + charge. Protons and neutrons have the same mass

ATOMIC THEORY -Electrons have a negative (-) charge -Electrons are found outside the nucleus, in orbital shells. -Electrons are MUCH smaller than protons and neutrons (about 1 1800 of the mass of a proton or a neutron) -Electrons have a negative (-) charge

Subatomic particle: the “parts” of an atom Protons Neutrons Electrons

Orbital shell: The space that the electron uses when it travels around the nucleus. The outside orbital shell is called the valence shell

Assignment: BIG BOOK p. 203-204

Chapter 4.1: The Periodic Table Vocabulary: matter, mass, volume, substance, chemical change, physical change, state, particle, gas, liquid, solid, attract

Vocabulary: ion atomic number atomic mass common ion charge metal non-metal transition metal period family / group alkali metal alkaline earth metal halogen noble gas

Atoms and Ions the number of protons = number of electrons Atoms are the smallest part of an element Atoms are NEUTRAL (no charge) the number of protons = number of electrons

Atoms and Ions Ions are an atom with an electrical charge Ions can have a + or – charge The number of electrons changes

Introduction to the Periodic Table Common ion charge Other ion charge Name Symbol Atomic number Average atomic mass

The number of protons determines what element it is Atomic Number = number of protons The number of protons DOES NOT CHANGE!! This would change what element it is!

INCREASING REACTIVITY

Atomic numbers get bigger as you go to the right and down

2. Electrons The number of electrons determines the charge. Electrons can be gained or lost from an atom. They are easy to lose because they are on the outside of the atom and they are VERY SMALL. Number of protons – Number of electrons = Charge

Ion: An atom or a molecule that has a charge Na loses an e-  Na+ Atom Ion

3. Neutrons The number of neutrons helps determine the mass of an atom. Atomic Mass: the mass of an atom. # of Protons + # of Neutrons = Atomic Mass

Organization of the Periodic Table In the periodic table elements are listed in order by their atomic number. Metals are on the left The transition metals range from group 3 -12 Non-metals are on the right

Transition Metals:

Metals: Easily LOSE electrons. Metals (left of zig zag line) Physical Properties of Metals: shiny good conductors of heat and electricity usually SOLIDS at room temperature Easily LOSE electrons.

Properties of Metals: Physical Properties of Metals: One metal that is not a solid at room temperature is Mercury (Hg)

Non-Metals: Easily GAIN electrons Non-metals (right of zig zag line) Physical Properties of Nonmetals: dull appearance poor conductors Easily GAIN electrons

Organization of the Periodic Table The horizontal rows are called periods

The vertical columns are called Families or groups

Group 2 = alkaline earth metals Group 17 = the halogens Elements in a family have similar properties and bond with other elements in similar ways. Group 1 = alkali metals Group 2 = alkaline earth metals Group 17 = the halogens Group 18 = noble gases 18 1 2 17 (c) McGraw Hill Ryerson 2007

Assignment: BIG BOOK p. 206-208

Chapter 4.1: Bohr Models

Vocabulary: valence electron valence shell stable octet Bohr model

Valence Shells The outside orbital shell is where elements react Valence Shell: the outside orbital shell Valence Electrons: the electrons that are in the valence shell Stable Octet: a full valence shell

BOHR MODELS Bohr diagrams show how many electrons appear in each orbital shell around an atom. The first electron shell holds 2 electrons The second electron shell holds 8 electrons The third electron shell holds 8 electrons The fourth electron shell holds 18 electrons

Bohr Models: The period number = the number of shells Except for the transition metals (family 3-12), the last digit of the group number = the number of electrons in the valence shell. See page 175 (c) McGraw Hill Ryerson 2007

a) Carbon # of shells = # of valence electrons = b) Neon # of shells = c) Magnesium # of shells = d) Iodine # of shells =

Bohr Models In Grade 10, we do not look at Bohr Models for the TRANSITION METALS, or elements with atomic number greater than 20

BOHR MODELS How to draw a Bohr Model: Draw a circle for the nucleus. Write the symbol, the #p and #n in the circle. 2) Draw circles outside the nucleus for the electron shells 3) Draw a dot (or write the #) for each electron in the electron shells.

Examples: Sodium Phosphorus Argon

BOHR MODELS What element is this? 18 p 22 n argon

HOMEWORK: BIG BOOK p. 211-213 Yellow workbook p. 60-61 (not #4)

Periodic Table and Ion Formation

Vocabulary: cation anion stable reactive

Periodic Table & Ion Formation Atoms gain and lose electrons to form bonds. Metals lose negative electrons & become positive ions. Positive ions are called CATIONS. See page 173 (c) McGraw Hill Ryerson 2007

Periodic Table & Ion Formation Atoms gain and lose electrons to form bonds. Non-metals gain electrons and become negative ions Negative ions are called ANIONS See page 173 (c) McGraw Hill Ryerson 2007

Bohr Models - Reactivity Elements want to be stable Stable means that the element isn’t affected by other elements It won’t explode, catch on fire or react when combined with other elements

Periodic Table & Ion Formation Every atom wants to have a stable octet like the nearest noble gas. Atoms form compounds to get a full valence shell like the closest noble gas in three ways: Lose electrons (metals) – form cation (+) Gain electrons (nonmetals) – form anion (-) Share electrons

Group 18: Noble Gases Noble gases (group 18) are STABLE Why?? They have a full valence shell They don’t form compounds They don’t react

Noble Gases:

Bohr Models - Reactivity Reactive means that the element will react with other elements Very reactive elements can explode or catch on fire easily

Bohr Models - Reactivity Group 1 elements are the MOST REACTIVE They even react with water! -They are reactive because their one valence electron is easy to give up

Na metal in water http://www2.uni-siegen.de/~pci/versuche/english/v44-1-1.html

Bohr Models - Reactivity Example: Na atom and Na ion  

Bohr Models - Reactivity Group 2 elements are also reactive -They want to lose two electrons -Group 17 elements are VERY REACTIVE -They want to gain an electron

Calcium metal in water: http://www.angelo.edu/faculty/kboudrea/demos/calcium_H2O/calcium_H2O.htm

Bohr Models - Reactivity Example: F atom and F ion  

Groups and Families Every atom wants to have a full valence shell like the nearest noble gas. Atoms can either: Lose electrons (metals) – + charge, CATION Gain electrons (non-metals) – - charge, ANION

Assignment: BIG BOOK p. 217-218

Forming Compounds

Vocabulary: ionic compound covalent compound Lewis diagram Diatomic molecule

Periodic Table & Ion Formation Atoms gain and lose electrons to form bonds. The atoms become ions. Ions can ATTRACT or REPEL one another.  + and – attract  + and + repel  - and - repel

Forming Compounds When two atoms get close together, their valence electrons react. valence electrons combine to form a bond Each atom in the compound wants a full valence shell

Forming Compounds  atoms share electrons. There are 2 types of compounds: 1) IONIC COMPOUND: metal + non-metal 2) COVALENT COMPOUND: non-metal + non-metal  atoms share electrons. See pages 176 - 177 (c) McGraw Hill Ryerson 2007

Ionic Compounds IONIC COMPOUNDS: metals lose electrons and non-metals take electrons. The - and + ions are ATTRACTED to each other and form a BOND. See pages 176 - 177 (c) McGraw Hill Ryerson 2007

Electrons are transferred from the positive ions to negative ions Ionic Compounds Example ionic bond: lithium and oxygen form an ionic bond in the compound Li2O. + lithium oxygen Electrons are transferred from the positive ions to negative ions Li+ O2- Li+ lithium oxide, Li2O See pages 176 - 177 (c) McGraw Hill Ryerson 2007

Covalent Compounds COVALENT COMPOUND: atoms share electrons. Covalent bonds form when electrons are shared between two non-metals. Electrons stay with their atom but are shared See pages 176 - 177 (c) McGraw Hill Ryerson 2007

Covalent Compounds Example covalent bond Hydrogen and fluorine form a covalent bond in the compound hydrogen fluoride. + Hydrogen fluoride hydrogen fluorine electrons are shared (c) McGraw Hill Ryerson 2007 See pages 176 - 177

Bohr Models of Compounds: Ionic Compounds: Rules: 1) Use square brackets to show the ions 2) Write the charge Examples: NaCl LiF2

Bohr Models of Compounds: Covalent Compounds: Electrons are shared Examples: H2O BF3

Assignment: BIG BOOK p. 224-227

Ch. 4.1: Lewis Diagrams

Lewis Diagrams A Lewis diagrams is simper than a Bohr Diagram. It just shows the valence shell or valence e-. Dots representing electrons are placed around the element symbols at the points of the compass (north, east, south, and west). N W E S

Lewis Diagrams - Basic Rules Write the symbol for the element 2. Place dots around symbol (● = electron). Place them like the 4 points of a compass. 3. Fill in dots one at a time until the 5th e- is reached, then pair. Try drawing the Lewis Diagrams for Hydrogen, Fluorine and Nitrogen:

Lewis Diagrams

Lewis Diagrams of Ions Lewis diagrams can be used to represent IONS and IONIC BONDS: For positive ions, one electron dot is removed For negative ions, one electron dot is added Square brackets are placed around each ion with the charge Examples: Li­+ B3+ N3- F-

Lewis Diagrams of Ions Lewis diagrams and IONIC Compounds: Square brackets are placed around each ion with the charge Example: BeCl2 – 2+ – • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • Be Cl Cl Be Cl Cl Be Cl Each beryllium has two electrons to transfer away, and each chlorine can receive one more electron. Since Be2+ can donate two electrons and each Cl– can accept only one, two Cl– ions are necessary. beryllium chloride See page 179 (c) McGraw Hill Ryerson 2007

Lewis Diagrams of Covalent Bonds Lewis diagrams and COVALENT BONDS: Valence electrons are drawn for each atom. Unpaired electrons are shared to form bonds. One shared pair of electrons = 1 bond (drawn as a line) See page 179 (c) McGraw Hill Ryerson 2007

Lewis Diagrams of Covalent Bonds Important note: 2 electrons are needed for 1 covalent bond 2 MORE electrons are needed for another covalent bond (a double bond) (double bond)

Lewis Diagrams of Diatomic Molecules DIATOMIC MOLECULE: Two atoms joined by covalent bonds. Example: O2 and H2 are also easy to draw as Lewis diagrams. Diatomic molecules form because they are more stable than atoms by themselves See page 180 (c) McGraw Hill Ryerson 2007

The SEVEN diatomic atoms are: Br2 I2 Cl2 F2 O2 N2 H2

Assignment: Finish the handout (Lewis diagrams), then… Chapter 4.1 Review in your blue Workbook: Read p. 57 (from ionic and covalent compounds) to 58. As you read, highlight or underline important terms. Do the questions on p.62 - 64