Ba 2 Si 3 CCHe 2 mistry

Introduction Laws of chemistry govern the structure and function of all living things!

Atoms a. simplest part of an element that retains all the properties of that element b. determine the behavior of matter c. subatomic particles protons (p+) positively charged particles neutrons (nº) no charge electrons (e-) negatively charged particles make up 99% of the mass d. Net electrical charge of an atom is zero because the number of p+ = e- e. e- located in orbitals (3-D space surrounding atom) 90% of time f. Electrons are the only particles involved in chemical reactions.

Orbital Shells a. valence electrons e- in outermost shell b. valence shells are complete (happy) when full c. 1 st orbital = 2 e- 2 nd orbital = 8 e- 3 rd orbital = 8 e- 4 th orbital = 16 e- methane CH 4 C H H H H Bohr Model nucleus 1 st shell maximum of 2 electrons 2 nd shell maximum of 8 electrons 3 rd shell maximum of 8 electrons 4 th shell maximum of 16 electrons

Matter a.Everything in the universe is made of matter. b.Anything that occupies space and has mass. c.Building blocks = atoms d.Properties: mass= quantity of matter volume= amount of space occupied density= mass/volume weight= pull of gravity Solid Strong bonds Liquids Weak bonds Gas No bonds Plasma Ionization + electron proton Phases of Matter

Forms of Matter a. element = pure substance made of only one kind of atom –cannot be chemically broken down into other substances –over 100 elements, but less than 30 support life –Carbon Hydrogen Oxygen Nitrogen (more than 90% of the mass of living things is made of these four elements) 6 C Carbon H Hydrogen O Oxygen N Nitrogen

b. Compound = two or more elements in a fixed ratio Examples: H O, CO, NaCl 22 Chemical formulas ratio of water = 2 hydrogen atoms to one oxygen atom c. Molecule = simplest part of a substance that retains all the properties of that substance H O – more than one type of atom 2 Forms both a molecule and a compound d. Both represent different combinations of atoms. O - one type of atom 2 Forms a molecule but not a compound.

Periodic Table of Elements a. Atomic Number (unique for each element) = # of protons in the nucleus = # of electrons in a neutral atom b. Atomic Mass = # of protons and neutrons in the nucleus 6 C Carbon Atomic number Chemical symbol Name Atomic Mass Al Mass number Atomic number 13 protons OR 13 electrons 13 protons AND 14 neutrons

Ion a. atoms that gain or lose electrons b. have an unequal number of p+ and e- c. have net negative or positive charge d. very reactive atoms SPECIAL ATOMS NaCl Na sodium ion Na + sodium

Isotopes a. atoms with the same number of protons but a different number of neutrons; different mass b. unstable nucleus; releases radiation; can damage living tissue c. Used in medicine and research 1. biological tracers 2. dating objects 3. treating cancer (SPECIAL ATOMS) 6P 6N Carbon 12 6P 8N Carbon 14

Formation of Compounds by Bonding a. compounds have 2 or more elements in a fixed ratio b. have new properties from atoms c. covalent bonds = 2 atoms share one or more valence electrons (forms molecules); very strong bond d. ionic bonds = transfer of electrons; formed by electrical attraction between two oppositely charged ions; (forms crystals)