SURVEY OF CHEMISTRY I CHEM 1151 CHAPTER 1 DR. AUGUSTINE OFORI AGYEMAN Assistant professor of chemistry Department of natural sciences Clayton state university

CHAPTER 1 MATTER

CHEMISTRY AND MATTER Chemistry - Is the study of matter and energy and the interactions between them - Involves studying the properties and behavior of matter Matter - Anything that has mass and occupies space Examples - Living and nonliving things - Things that can be seen: animals, plants, soil, water, clothes, books - Things that cannot be seen: air, bacteria

CHEMISTRY AND MATTER Energy - The ability to do work - Forms of energy (sound, heat, light) are NOT considered to be matter Mass - Amount of matter in an object Volume - The amount of space that the matter takes up

CHEMISTRY AND MATTER Difference between Mass and Weight Mass - is a measure of total quantity of matter in an object - constant and independent of location - instrument: the mass balance Weight - is a measure of the force exerted on an object by gravitational force - weight = mass x gravitational force - changes with location (e.g. gravitational attraction on the moon is 1/6th that on the earth) - instrument: spring scale

PHYSICAL STATES OF MATTER Three physical states of matter: solid, liquid, and gas Solid - Has a definite shape and a definite volume Examples ice, book, table, TV set

PHYSICAL STATES OF MATTER Three physical states of matter: solid, liquid, and gas Liquid - Has an indefinite shape and a definite volume - Always takes the shape of its container (the portion it occupies) Examples drinking water, juice

PHYSICAL STATES OF MATTER Three physical states of matter: solid, liquid, and gas Gas - Has an indefinite shape and an indefinite volume - Always completely fills its container, taking the shape and volume of the container Examples air, water vapor (steam)

PHYSICAL STATES OF MATTER State of matter depends on: - Temperature - Surrounding pressure - Strength of forces holding the structural particles together - Water can be found in all three physical states: solid ice, liquid water, and gaseous steam.

PROPERTIES OF MATTER Two categories: physical and chemical properties Physical Property - Does not change the identity or composition of a substance - Does not involve changing a substance into another Examples shape, color, odor, density, taste, feel, mass, volume phase, melting point, boiling point, hardness

PROPERTIES OF MATTER Two categories: physical and chemical properties Chemical Property - Involves changing a substance into another substance (chemical reactions) - Describes the reactivity of a material Examples heat of combustion, flammability, enthalpy of formation, explosiveness, toxicity, ionization potential, electronegativity

PROPERTIES OF MATTER Two categories: physical and chemical properties Chemical Property - Failure to undergo a chemical change is also considered a chemical property Examples - inability of glass to burn - gold not reacting with water

Two categories of changes in matter: physical and chemical changes Physical Change - When a substance changes its physical appearance but not its chemical composition Examples - change of state (from liquid to gas, from liquid to solid, etc.) - when liquid water evaporates to steam or freezes to ice PROPERTIES OF MATTER

Two categories of changes in matter: physical and chemical changes Chemical Change - When a substance undergoes a change in chemical composition - Undergoes a chemical reaction - Converts into one or more new substances Examples - rusting of iron exposed to moist air - combustion of methane - burning of hydrogen in air PROPERTIES OF MATTER

Properties can also be divided into extensive and intensive Extensive Property - Depends on the amount of sample under investigation Examples mass, volume Intensive Property - Does not depend on the quantity of sample - Determines the identity of the sample Examples melting point, boiling point, density

CHEMICAL COMPOSITION Substance A material that is chemically the same throughout Pure Substance - Matter that has distinct properties and definite composition - Cannot be separated into other kinds of matter by any physical means Examples pure water, pure salt

Elements - Pure substances that cannot be reduced to simpler substances by normal chemical means - Fundamental building blocks of all matter Examples silver, carbon, sodium, oxygen, hydrogen - Note that O 2, N 2, S 8, are elements CHEMICAL COMPOSITION

Elements elements are known at present - 92 are naturally occurring and 25 are synthesized in the laboratory - Only 5 elements account for over 90% of Earth’s crust (oxygen, silicon, aluminum, iron, and calcium) - Only 3 elements account for over 90% of the human body mass (oxygen, carbon, hydrogen) CHEMICAL COMPOSITION

Elements The symbol for each element consists of one or two letters derived from the element’s name, with the first letter capitalized Some elements and their symbols Carbon C Aluminum Al Barium Ba Beryllium Be Copper Cu Flourine F Iron Fe Gallium Ga Germanium Ge Hydrogen H Helium He Mercury Hg Iodine I Lithium Li Magnesium Mg Manganese Mn Nitrogen N Sodium Na Nickel Ni Oxygen O Phosphorus P Lead Pb Platinum Pt Sulfur S CHEMICAL COMPOSITION

Compounds - Pure substances that can be broken into two or more simpler pure substances by chemical means - Combination of two or more elements Examples Water (H 2 O), carbon dioxide (CO 2 ), sodium chloride (NaCl) CHEMICAL COMPOSITION

Mixture - A combination of two or more pure substances Examples grains of rice and wheat cereal and sugar salt and sand - Components of a mixture can be separated by physical means (filtration, distillation, the use of magnet for metals)

CLASSIFICATION OF MIXTURES Homogeneous Mixture (Solution) - Is uniform throughout - Contains only one visibly distinct phase Examples - sugar or salt dissolved in water - glass - alloys (copper & tin → Bronze) (iron, carbon, chromium, and other substances → stainless steel) - air (homogeneous mixture of nitrogen, oxygen, and other substances)

CLASSIFICATION OF MIXTURES Heterogeneous Mixture - Does not have the same composition - Contains visibly different phases Examples rocks, wood, soils - Physical combination of substances produces a mixture - Chemical combination of substances produces a compound

MATTER PURE SUBSTANCE MIXTURE ELEMENTCOMPOUND HOMOGENEOUS MIXTURE HETEROGENEOUS MIXTURE CLASSES OF MATTER