What is Chemistry? -the study of the composition and reactions of matter. What is matter? What are the states of matter? What is matter composed of?

Elements 92 naturally occurring elements LET’S NAME THEM! Name the most common elements? - a pure substance that can not be broken down or converted to other substances by ordinary chemical means. NO! CarbonHydrogenOxygenNitrogen Phosphorus Sulfur 18.5 %9.5 %65 %3.3 % 96.3 % of the human body

What are elements composed of? Atoms What are atoms composed of? - the basic unit of matter Subatomic particles Protons- (+) positively charged particles Neutrons- (0) uncharged particles Electrons- (-) negatively charged particles

Atoms are neutral Atomic number of an atom - the number of protons within an atom Protons and Neutrons have mass Why?(+) = (-) Atomic mass of an atom - the protons + neutrons C 12 6 Atom of Carbon

Isotopes - atoms of the same element that have the same atomic #, but different atomic mass. C 12 6 Carbon 12Carbon 14 C 14 6 Radioactive Isotopes - isotopes that have unstable nuclei that decay and emit radiation. Nuclei with too many neutrons break apart spontaneously (decay), which can be detected

Uses of radioactive isotopes - Labels and Therapy PET scan

How are subatomic particles arranged? Ex. Carbon Ex. Chlorine Which electrons contain the most energy?

Why is electron configuration important? - Formation of molecules and compounds Molecule – a stable assembly of 2 or more atoms. Compound - 2 or more atoms of different elements bonded together in fixed proportions. Ex. O 2 Ex. H 2 O

How are molecules and compounds formed? Chemical reactions Ex. 2H + OH2OH2O How do they stay together? Chemical Bonds - An attractive force that arise between 2 atoms when their electrons interact. 3 types of Bonds: Ionic, Covalent, and Hydrogen

Ionic Bonds - form when electrons are transferred from one atom to another. Ex. Na + Cl = Na + Cl - Cl at# = 17Na at# = 11

Ionic Bonds - form when electrons are transferred from one atom to another. Ex. Na + Cl = Na + Cl - Cl #e- = 18Na #e - = 10

Covalent Bonds - form from the sharing of e- 2 types of covalent bonds: 1. Non-polar covalent bonds - results from the equal sharing of e- 2. Polar covalent bonds - results from the unequal sharing of e-

Ex.H - H 1. Non-polar covalent bonds

Ex.O = O 1. Non-polar covalent bonds

Ex.H2OH2O 2. Polar covalent bonds

Hydrogen bonds - weak electrical attractions between “H” and a negatively charged atom of another molecule. Water molecules DNA