Introduction to Matter Measuring Matter Changes in Matter Elements and Atoms Table of Contents Book K – pgs Book K pgs 48-53

Introduction to Matter Ch. 1 Sec. 2 “Measuring Matter” Book K – pgs International System of Units - The system of units (SI) used by scientists to measure the properties of matter. Weight - A measure of the force of gravity on an object. Mass - A measure of how much matter is in an object. Measured in units such as gram (g), kilogram (kg) Unlike weight, mass does not change with location, even when the force of gravity on an object changes.

Introduction to Matter Ch. 1 Sec. 2 “Measuring Matter” Book K – pgs 16-20

Introduction to Matter Calculating Density A small block of wood floats on water. It has a mass of 200 g and a volume of 250 cm 3. What is the density of the wood? Read and Understand What information are you given? Mass of block = 200 g Volume of block = 250 cm 3 - Measuring Matter

Introduction to Matter Calculating Density A small block of wood floats on water. It has a mass of 200 g and a volume of 250 cm 3. What is the density of the wood? Plan and Solve What quantity are you trying to calculate? The density of the block = ? What formula contains the given quantities and the unknown quantity? Density = Mass / Volume Perform the calculation. Density = Mass / Volume = 200 g / 250 cm 3 = 0.80 g/cm 3 - Measuring Matter

Introduction to Matter Calculating Density A small block of wood floats on water. It has a mass of 200 g and a volume of 250 cm 3. What is the density of the wood? Look Back and Check Does your answer make sense? The density is lower than 1.0g/cm 3, which makes sense because the block can float. - Measuring Matter

Introduction to Matter Calculating Density Practice Problem A sample of liquid has a mass of 24 g and a volume of 16 mL. What is the density of the liquid? 1.5 g/mL - Measuring Matter

Introduction to Matter Calculating Density Practice Problem A piece of solid metal has a mass of 43.5 g and a volume of 15 cm 3. What is the density of the metal? 2.9 g/cm 3 - Measuring Matter

Introduction to Matter Density Click the Video button to watch a movie about density. - Measuring Matter

Introduction to Matter More on Measuring Matter Click the PHSchool.com button for an activity about measuring matter. - Measuring Matter

Solids, Liquids, and Gases Ch. 2 Sec. 2 “Changes of States” Book K pgs Changes Between Solid and Liquid Melting – The change in state from a solid to a liquid. In pure substances it occurs at an exact temperature called the melting point. Melting point of pure water = 0ºC Energy (heat) that is added to the stationary molecules cause them to vibrate. At melting point, the particles of a solid substance are vibrating so fast that they break free from their fixed positions.

Solids, Liquids, and Gases Ch. 2 Sec. 2 “Changes of States” Book K pgs Changes Between Solid and Liquid Freezing – The change of state from liquid to solid At its freezing point, the particles of a liquid are moving so slowly that they begin to form regular patterns Freezing point of pure water = 0ºC

Solids, Liquids, and Gases Ch. 2 Sec. 2 “Changes of States” Book K pgs Changes Between Liquid and Gas Vaporization – change from liquid to gas Liquid particles gain enough energy to form a gas Two types – evaporation and boiling Evaporation – vaporization that takes place on the surface of a liquid Boiling – vaporization both at and below the surface Boiling point – temperature at which liquid boils Is dependent on air pressure – the lower the pressure, the less energy is needed to make the molecules boil Ex: Sea Level – water boils at 100ºC; Denver (1600m) – water boils at 95ºC

Solids, Liquids, and Gases Ch. 2 Sec. 2 “Changes of States” Book K pgs Changes Between Liquid and Gas Condensation – change from gas to liquid Occurs when particles in a gas lose enough thermal energy to form a liquid Ex: Clouds NOTE: Water vapor is invisible. Clouds, Fog, and Steam are all liquid droplets of water suspended in the air.

Solids, Liquids, and Gases Ch. 2 Sec. 2 “Changes of States” Book K pgs Changes Between Solid and Gas Sublimation – occurs when particles of a solid gain enough energy that they form a gas They do not pass through a liquid state Ex: Dry ice (frozen CO 2 )

Solids, Liquids, and Gases Temperature and Changes of State A beaker of ice at – 10ºC was slowly heated to 110ºC. The changes in the temperature of the water over time were recorded. The data were plotted on the graph shown here. - Changes of State

Solids, Liquids, and Gases Temperature and Changes of State Temperature (ºC) on the y- axis, time (minutes) on the x- axis Reading Graphs: What two variables are plotted on the graph? - Changes of State

Solids, Liquids, and Gases Temperature and Changes of State The temperature is rising from 0ºC to 100ºC. Reading Graphs: What is happening to the temperature of the water during segment C of the graph? - Changes of State

Solids, Liquids, and Gases Temperature and Changes of State Segment B: melting point of ice; segment D: boiling point of water Interpreting Data: What does the temperature value for segment B represent? For segment D? - Changes of State

Solids, Liquids, and Gases Temperature and Changes of State Change from solid to liquid; change from liquid to gas Drawing Conclusions: What change of state is occurring during segment B of the graph? For segment D? - Changes of State

Solids, Liquids, and Gases Temperature and Changes of State Water molecules in segment E have more thermal energy because they are at a higher temperature. Inferring: In which segment, A or E, do the water molecules have more thermal energy? Explain your reasoning. - Changes of State

Solids, Liquids, and Gases Data Sharing Lab Click the PHSchool.com button for an activity about sharing data for the Skills Lab Melting Ice. - Changes of State

Atoms and Bonding Ch. 1 Sec. 1 “Elements and Atoms” Book L pgs REVIEW Matter – anything that has a mass and takes up space Elements – simplest pure substance that cannot be broken down (one type of atom) Compound – pure substance of two or more elements chemically combined in a specific ratio Mixture – two or more substances in the same area not chemically combined. Atom – smallest particle of an element or the basic unit of matter Protons (+) and Neutrons (o) in the nucleus Electrons (-) orbit outside the nucleus

Atoms and Bonding - Elements and Atoms The Building Blocks of Matter Matter may consist of elements, compounds, or mixtures.

Atoms and Bonding Ch. 1 Sec. 1 “Elements and Atoms” Book L pgs REVIEW Scientific theory - a well-tested idea that explains and connects a wide range of observations. Model – physical, mental, visual, and other representations of an idea to help people understand a concept that they cannot observe directly.

Atoms and Bonding Ch. 1 Sec. 1 “Elements and Atoms” Book L pgs REVIEW John Dalton’s Model All elements are made of atoms that cannot be divided. All atoms of the same element are exactly alike and have the same mass. Atoms of different elements are different and have different masses. An atom of one element cannot be changed into an atom of a different element. Atoms cannot be created or destroyed in any chemical change, only rearranged. Every compound is made of atoms of different elements, combined in a specific ratio.

Atoms and Bonding - Elements and Atoms Ch. 1 Sec. 1 “Elements and Atoms” Book L pgs REVIEW Dalton thought that atoms were like smooth, hard balls that could not be broken into smaller pieces.

Atoms and Bonding - Elements and Atoms Ch. 1 Sec. 1 “Elements and Atoms” Book L pgs REVIEW JJ Thomson Model (1897) Suggested that atoms had negatively charged electrons embedded in a positive sphere.

Atoms and Bonding - Elements and Atoms Ch. 1 Sec. 1 “Elements and Atoms” Book L pgs REVIEW Earnest Rutherford Model (1911) Performed an experiment where he shot positively charged particles through a thin sheet of gold foil Some particles were deflected (same charges repel) Led him to propose an atomic model with a positively charged nucleus.

Atoms and Bonding Ch. 1 Sec. 1 “Elements and Atoms” Book L pgs REVIEW Niels Bohr Model (1913) Showed electrons having specific amounts of energy causing them to stay in certain orbits Model showed flat orbital planes Orbital Cloud Model– (1920) electrons orbit the nucleus in multiple planes, creating a “negatively charged cloud” Amount of energy is related to how tightly they are held (increased energy = looser hold)

Atoms and Bonding - Elements and Atoms Ch. 1 Sec. 1 “Elements and Atoms” Book L pgs REVIEW Modern Atomic Theory (1932) – discovery of neutrons in the nucleus (similar mass to protons but no charge)

Atoms and Bonding More on Atomic Structure Click the PHSchool.com button for an activity about atomic structure. - Elements and Atoms

Atoms and Bonding Valence Electrons and Bonding The Periodic Table Ionic and Covalent Bonds Molecular Compounds Acids and Bases Table of Contents

Atoms and Bonding Valence Electrons and Bonding Valence electrons - The electrons that are in the highest energy level of an atom and that are involved in chemical reactions. The number of valence electrons in an atom of an element determines many properties of that element, including the ways in which the atom can bond with other atoms. - Atoms, Bonding, and the Periodic Table

Atoms and Bonding - Atoms, Bonding, and the Periodic Table Valence Electrons and Bonding Electron dot diagram - A representation of the valence electrons in an atom, using dots. Most elements that have a full set of valence electrons are “stable” or “unreactive” Ex. Nobel gases – Neon, Argon, Krypton

Atoms and Bonding Valence Electrons and Bonding When the valence shell of an atom is not full, one of two things can happen: 1.It will either take or share electrons from another atom to make it full 2.It will give up some loosely held electrons to make the new valence shell full Both scenarios make the atom “reactive” and a chemical bond will form Chemical bond - the force of attraction that holds two atoms together as a result of the rearrangement of electrons between them. - Atoms, Bonding, and the Periodic Table

Atoms and Bonding - Atoms, Bonding, and the Periodic Table The Periodic Table The periodic table is a system used worldwide for organizing elements into categories Elements are organized into rows and columns based on their atomic number.

Atoms and Bonding The Periodic Table Symbol - one- or two-letter set of characters that is used to identify an element. Atomic number - the number of protons in the nucleus of an atom. Elements are arranged in order of increasing atomic number. Period - elements in the same horizontal row of the periodic table. Group/family - elements in the same vertical column of the periodic table. - Atoms, Bonding, and the Periodic Table

Atoms and Bonding Periodic Table Activity Click the Active Art button to open a browser window and access Active Art about the periodic table. - Atoms, Bonding, and the Periodic Table

Atoms and Bonding - Atoms, Bonding, and the Periodic Table The Periodic Table As the number of protons (atomic number) increases, the number of electrons also increases. As a result, the properties of the elements change in a regular way across a period. A period ends when the highest energy level has eight electrons. The valence electrons of atoms in the next period are in a higher level so atoms in a group always have the same number of valence electrons

Atoms and Bonding - Atoms, Bonding, and the Periodic Table The Periodic Table Noble gas - an element of Group 18 of the periodic table. Typically “unreactive” The variety of colors in a “neon” sign results from passing an electric current through sealed glass tubes containing different noble gases.

Atoms and Bonding The Periodic Table Reactive Metals/Non-metals Halogen - an element belonging to Group 17 of the periodic table that has 7 valence electrons React easily with other elements whose atoms can give up or share electrons. Alkali metal – an element belonging to group 1 that have only one valence electron Can become chemically more stable by losing their one valence electron. - Atoms, Bonding, and the Periodic Table

Atoms and Bonding The Periodic Table Other Metals Most have one, two, or three valence electrons. React by losing these electrons, especially when they combine with oxygen or one of the halogens. Other Non-metals All of the nonmetals have four or more valence electrons. Become stable when they gain or share enough electrons to have a set of eight valence electrons. - Atoms, Bonding, and the Periodic Table

Atoms and Bonding The Periodic Table Metalloids Elements that lie along a zigzag line between the metals and nonmetals Depending on the conditions, these elements can behave as either metals or nonmetals Have from three to six valence electrons and can either lose or share electrons when they combine with other elements - Atoms, Bonding, and the Periodic Table

Atoms and Bonding - Ionic Bonds Ions and Ionic Bonds Ion - an atom or group of atoms that has an electric charge When an atom loses an electron, it loses a negative charge and become a positive ion. When an atom gains an electron, it gains a negative charge and becomes a negative ion.

Atoms and Bonding - Ionic Bonds Ions and Ionic Bonds You and a friend walk past a market that sells apples for 40 cents each and pears for 50 cents each. You have 45 cents and want an apple. Your friend also has 45 cents but wants a pear.

Atoms and Bonding Ions and Ionic Bonds Polyatomic ion - an ion that is made of more than one atom. group of atoms that reacts as a unit have an overall positive or negative charge - Ionic Bonds

Atoms and Bonding - Ionic Bonds Ions and Ionic Bonds Ionic bond - the attraction between two oppositely charged ions Form as a result of the attraction between positive and negative ions. Ionic compound - a compound that consists of positive and negative ions.

Atoms and Bonding Chemical Formulas and Names Chemical formula - a combination of symbols that represents the elements in a compound. Subscript - number in a chemical formula that tells the number of atoms in a molecule or the ratio of elements in a compound. When ionic compounds form, the ions come together in a way that balances out the charges on the ions. The chemical formula for the compound reflects this balance. For an ionic compound, the name of the positive ion comes first, followed by the name of the negative ion. Ex: MgO is named magnesium oxide; NH 4 NO 3, named ammonium nitrate - Ionic Bonds

Atoms and Bonding - Ionic Bonds Properties of Ionic Compounds In general, ionic compounds are hard, brittle crystals that have high melting points. When dissolved in water or melted, they conduct electricity. Crystal - an orderly, 3-D pattern of ions or atoms in a solid. Every ion is attracted to ions of opposite charge that surround it The pattern remains the same no matter what the size of the crystal Ions in water can increase the melting point and the electrical conductivity

Atoms and Bonding Salt Click the Video button to watch a movie about salt. - Ionic Bonds

Atoms and Bonding Links on Ionic Compounds Click the SciLinks button for links on ionic compounds. - Ionic Bonds

Atoms and Bonding How Covalent Bonds Form Covalent bond – a chemical bond formed when two atoms share electrons. usually form between atoms of nonmetals The force that holds atoms together in a covalent bond is the attraction of each atom’s nucleus for the shared pair of electrons. Molecule – a neutral particle made of two or more atoms joined by covalent bonds. - Covalent Bonds

Atoms and Bonding - Covalent Bonds How Covalent Bonds Form The number of covalent bonds that nonmetal atoms can form equals the number of electrons needed to make a total of eight (or a full outer shell) The oxygen atom in water and the nitrogen atom in ammonia are each surrounded by eight electrons as a result of sharing electrons with hydrogen atoms.

Atoms and Bonding How Covalent Bonds Form Double bond - a chemical bond formed when atoms share two pairs of electrons. Triple bond - a chemical bond formed when atoms share three pairs of electrons. An oxygen molecule contains one double bond, while a carbon dioxide molecule has two double bonds. A nitrogen molecule contains one triple bond. - Covalent Bonds

Atoms and Bonding - Covalent Bonds Molecular Compounds Molecular compound - a compound that is composed of molecules Compared to ionic compounds, molecular compounds generally have lower melting points and boiling points, and they do not conduct electricity when dissolved in water.

Atoms and Bonding Comparing Molecular and Ionic Compounds The table compares the melting points and boiling points of a few molecular compounds and ionic compounds. Use the table to answer the following questions. - Covalent Bonds

Atoms and Bonding Comparing Molecular and Ionic Compounds Check that the graphs are correctly set up and labeled before students plot the data. Graphing: Create a bar graph of just the melting points of these compounds. Arrange the bars in order of increasing melting point. The y-axis should start at – 200ºC and go to 900ºC. - Covalent Bonds

Atoms and Bonding Comparing Molecular and Ionic Compounds Melting points of molecular compounds are lower than those of ionic compounds. Interpreting Data: Describe what your graph reveals about the melting points of molecular compounds compared to those of ionic compounds. - Covalent Bonds

Atoms and Bonding Comparing Molecular and Ionic Compounds Molecular compounds have weak attractive force between molecules, so less energy is needed to melt molecular compounds. Inferring: How can you account for the differences in melting points between molecular compounds and ionic compounds? - Covalent Bonds

Atoms and Bonding Comparing Molecular and Ionic Compounds Boiling points of molecular compounds are lower than those of ionic compounds. Interpreting Data: How do the boiling points of the molecular and ionic compounds compare? - Covalent Bonds

Atoms and Bonding Comparing Molecular and Ionic Compounds Students may predict that ammonia is a molecular compound because it has relatively low melting and boiling points. Predicting: Ammonia’s melting point is –78ºC and its boiling point is –34ºC. Is ammonia a molecular compound or an ionic compound? Explain. - Covalent Bonds

Atoms and Bonding Unequal Sharing of Electrons Atoms of some elements pull more strongly on shared electrons than do atoms of other elements. As a result, the electrons are pulled more toward one atom, causing the bonded atoms to have slight electrical charges. Polar bond - a covalent bond in which electrons are shared unequally Nonpolar bond - a covalent bond in which electrons are shared equally. - Covalent Bonds

Atoms and Bonding - Covalent Bonds Unequal Sharing of Electrons Fluorine forms a nonpolar bond with another fluorine atom. In hydrogen fluoride, fluorine attracts electrons more strongly than hydrogen does, so the bond formed is polar.

Atoms and Bonding - Covalent Bonds Unequal Sharing of Electrons A carbon dioxide molecule is a nonpolar molecule because of its straight-line shape. In contrast, a water molecule is a polar molecule because of its bent shape.

Atoms and Bonding Links on Molecular Compounds Click the SciLinks button for links on molecular compounds. - Covalent Bonds

Acids, Bases, and Solutions Properties of Acids Acid – a substance that tastes sour, reacts with metals and carbonates, and turns blue litmus red. Ex: hydrochloric acid, nitric acid, sulfuric acid, carbonic acid, and acetic acid.

Acids, Bases, and Solutions - Describing Acids and Bases Properties of Acids and Bases Litmus is an example of an indicator, a compound that changes color when in contact with an acid or a base.

Acids, Bases, and Solutions - Describing Acids and Bases Uses of Acids and Bases Acids and bases have many uses around the home and in industry.

Acids, Bases, and Solutions QuestionAnswer Asking Questions Before you read, preview the red headings. In a graphic organizer like the one below, ask a what question for each heading. As you read, write answers to your questions. What is an acid? An acid is a substance that tastes sour, reacts with metals and carbonates, and turns blue litmus paper red. What is a base? A base is a substance that tastes bitter, feels slippery, and turns red litmus paper blue. What are uses of acids and bases?Uses of acids include cleaning products, fertilizers, and car batteries; uses of bases include cleaning products, baking ingredients, and cement manufacturing. - Describing Acids and Bases

Acids, Bases, and Solutions Links on Acids and Bases Click the SciLinks button for links on acids and bases. - Describing Acids and Bases

Acids, Bases, and Solutions End of Section: Describing Acids and Bases