Chemistry - the study of…
structure and behaviors of atoms and molecules
4 main classes of biological molecules
- carbohydrates
- lipids
- proteins
- nucleic acids
Elements
pure substances in periodic table
H
Atomic #?
Atomic mass?
Hydrogen
- atomic # = 1
- atomic mass = 1
Ag
Silver
O
Atomic #?
Atomic mass?
Oxygen
- atomic # = 8
- atomic mass = 16
-HAS COVALENT BONDS
Compounds
combinations of elements
CO2
carbon dioxide
HCl
hydrochloric acid
living organisms are made up of what elements? (6)
(C) arbon (H) ydrogen (O) xygen (P) hosphorus (S) elenium (N) itrogen
ATOMS =
- protons
- neutrons
- electrons
Nucleus
- set # of protons
- # neutrons may very
Atomic number
-# of protons (in nucleus)
-
Atomic mass (AMU) =
protons + # neutrons
First energy shell can hold…
2 e-
Second energy shell can hold…
8 e-
***LIKE TO HAVE 8 ELECTRONS IN OUTTER SHELL
Inner shells are filled before
outer shells
Isotopes
same form of element, w/ different #’s of neutrons
Radioactive isotopes
unstable, may emit energy when changes to a stable form
Ions
ATOMS with + or - charges
ex. H+, Cl-
Molecules
2 or more atoms bonded together
Covalent Bonds
- atoms share pairs of e-
- FOUND IN MOLECULES
Non-polar Bonds
e- shared EQUALLY
ex. O2, CH4
Polar Bonds
e- shared UNEQUALLY
ex. H2O
Ionic Bonds
- bonds btwn oppositely charged ions
ex. salt
Hydrogen Bonds
-when a partially (+) HYDROGEN is attracted to partially (-) ATOM
Hydrogen Bonding makes…
life possible
Hbonds affect physical…
- properties of water
- why water is slow to heat
- unusual amount of heat is required to evaporate water
ex. sweating
**Behavior of water is affected by…
cohesion and adhesion
Cohesion
like molecules cling together
Adhesion
UNLIKE molecules cling together
Ice is LESS dense than…
- water
- floats on water
ex. frozen layer of a lake
Water is a
solvent
Solvent
does the dissolving
Solute
- dissolves in solvent
ex. polar molecules, ions
HydroPHILIC
- dissolves in water
ex. salt, sugar
HydroPHOBIC
does NOT dissolve in water
ex. oil, fats
Acids
release H+ when dissolved in water
Base
accepts H+ when dissolved in water
Acidi pH #’s
0 - 7
Basic pH #’s
7 - 15
Neutral pH #
7
Buffers
- moderate changes in pH
- absorb or release H+
ex. bicarbonate/carbonic acid buffering system in blood
Neutrons =
atomic mass - atomic #
neutrons =
atomic mass - atomic #
Hbonds are ______ than covalent bonds
WEAKER
Mass is always the BIGGER…
in periodic table
Hydrogen Bonds are usually…
-btwn 2 different molecules
______ bonds allow bugs to walk on water
hydrogen
Water is an example of ______ bond
Polar
Salt has _____bonds
Ionic