Chemistry

Matter Matter = something that has mass and takes up space (has volume)

Matter Solid Liquid Gas comes in 3 main phases (plasma is outside our scope)

Solid Definite Shape Definite Volume

Liquid Indefinite Shape – takes the shape of the container Definite Volume

Gas Indefinite Shape – takes the shape of the container Indefinite Volume – can expand and be compressed

Elements one of the 100+ pure substances that make up everything in the universe

Examples of Elements H= Hydrogen C= Carbon O= Oxygen N= Nitrogen S= Sulfur Na= Sodium Ca= Calcium K= Potassium I= Iodine Cl= Chlorine P= Phosphorus

Atom the smallest particle considered an element

Sub-atomic Particles Protons p+ p+ - positive charge, in nucleus Electrons - e - negative charge, orbiting nucleus Neutrons n0 n0 – no charge, in nucleus

Composition of Matter The protons and neutrons are found at the center of the atom and are located in the nucleus. Atomic number: number of protons in the nucleus Atomic mass: number of protons + neutrons in the nucleus

Composition of Matter Atomic number = 1Atomic number = 2 Atomic mass = 1 Atomic mass = 4

Drawing an Atom of Carbon C Atomic Mass Atomic # minus Atomic # = # of n0n0 = # p+ p+ and # of e-e- Carbon has 6 p + and 6 e - Carbon has 6 n 0

Drawing an Atom of Carbon 6 p + 6 n 0 e-e- e-e- e-e- e-e- e-e- e-e-

Inert (Stable) Elements Have complete valence shells and are stable Octet Rule –Outer shell must be full for atom to be stable –Shell 1 has 2 electrons –Shell 2 has 8 electrons 10 = –Shell 3 has 8 electrons 18 = Figure 2.4a

Isotopes Isotopes: atom of the same element that has a different number of neutrons Identified by the mass number –Carbon-12, carbon-13, and carbon-14 Radioactive isotopes: their nuclei are unstable and break down at constant rate over time.

Compounds - 2 or more elements chemically combined to form a new substance with new properties Properties – The way a chemical substance looks and behaves

Compounds Compounds – are made of 2 or more different atoms combined to form Molecules H + O H 2 O = H O H Chemical formula lists the number of different atoms in a single molecule Structural formula shows the arrangement of the atoms in a single molecule

Molecules Glucose Sugar C 6 H 12 O 6 Chemical formula C H OH CC C CC H H H H H H OH O O H H O OH Structural formula

Compounds Inorganic Compounds or Organic Compounds usually don’t contain Carbon generally come from the earth generally simple molecules always contain C & H and usually O, N, sometimes S & P originate in organisms generally complex molecules

Examples of Inorganic Compounds H + O = H 2 O = Water H + Cl = HCl = Hydrochloric Acid C + O = CO 2 = Carbon Dioxide Na + Cl = NaCl = Common Table Salt

Examples of Organic Compounds C, H + O Carbohydrates = Sugars, starches & cellulose C, H + O Lipids = Fats & Oils C, H, O, N, & sometimes P + S Proteins C, H, O, N, + P Nucleic Acids – DNA & RNA

Interactions of Matter Chemical bonds: 1.bond atoms to form compounds, 2.are formed according to the number of electrons in the outermost energy level, and 3.will not form when an atom has a full outer energy level

Interactions of Matter To achieve stability, an atom will gain, lose, or share electrons.

Interactions of Matter Ionic bonds: formed by transfer of electrons –Ion: charged atom; Ions form when ionic bonds occur. Ionic bonding-- electrons are transferred Chlorine (Cl)Sodium (Na)

sodium (Na) chlorine (Cl) Ionic bonding in sodium chloride (NaCl)

Interactions of Matter Covalent bond: formed by sharing of electrons Co:together, valent: valence involve outermost energy level only very strong Covalent bonding-- electrons are shared Oxygen (O)

Covalent bonding

Intermolecular Forces van der Waals Forces –Attraction charge between the molecules

Summary:

Quiz 1.What is a atom? 2.What are the 3 subatomic particles in an atom? 3.What does the atomic number indicate? 4.If an atom has an atomic number of 35, how many electrons does it have? 5.How many electrons are on the first shell? 6.What type of bond shares electrons? 7.What type of bond gains or loses electrons?

Quiz-Answers 1.The smallest particle of an element or basic unit of matter 2.Proton, neutron, and electron 3.Number of protons Covalent Bond 7.Ionic Bond

Interactions of Matter Chemical reaction: any process in which a chemical change occurs –If energy is released → spontaneous –If energy is required → will NOT occur without adding energy

Interactions of Matter Reaction formulas: represent chemical reactions; the arrow means “react to form” –Example: O 2 + 2H 2 → 2H 2 O Catalyst: a chemical that speeds a reaction up to 10,000,000,000 times faster