Chap. 2 : Chemistry
I.
Makeup of matter
--- matter – anything that has
mass and takes up space.
(volume)
A. Atoms – simplest particle of an
element.
1. Nucleus – center of atom,
contains protons (p+) and neutrons
(n).
p+ + n = atomic mass
2. electrons – (-) charge, orbit
around nucleus in shells or orbitals.
3. neutrons (n) – atomic mass –
atomic number
*** atomic number – tells # of
p+, e-.
B. Orbitals
- family – row going down, tells # of
e- in outer shell.
- period – row going across, tells the
# of electron shells.
*** All atoms want to be stable !!
Stable arrangements are having a
full outer shell which is 8e- or 2e-(if
only 1 shell)
*** e- in shells :
1st – 2e2nd – 8e3rd – 18e4th – 7th – 32eC. Bonding – atoms bond to become
stable.
1. Ionic bonds – transfer of e-,
forms ions. Done between families
1,2,3,5,6,7 . Ex. Na + Cl
NaCl
2. Covalent – sharing of e-. Done with
family 4 and also H.
Ex. H + Cl
HCl
D. Elements – purest substance –
cannot be broken down into
anything simplier.
--- elements combine to form
compounds. Ex. H2O , C6H12O6
--- molecule – smallest part of a
compound.
II. Energy – ability to do work
-- activation energy – amount of
energy needed to start a chemical
reaction. (enzymes lower activation
energy)
III. Chemical Reactions
A. Na + Cl
NaCl
(reactants)
(yields)
(products)
-- subscript – tells # of
atoms of 1 particular element.
Ex. H2(subscript)
-- coefficient – tells # of
molecules of a particular element or
compound. Ex 2H O
2
(2 molecules of water)
** subscript x coefficient = total
# of atoms of a particular
element.
ex. 6C4H8O4
___ C ___ H ___ O
B. Energy Transfer in Reactions
1. Exergonic Reactions –
release energy (feel hot)
2. Endergonic reactions – absorb
energy (feel cold).
IV. Solutions
- mixture of one or more
substances. Made up of :
a. – substance being dissolved
solute.
b. solvent – substance being
dissolved into.
ex. Sugar (solute) water(solvent)
IV. Acids/Bases
1. Hydroxide ion (OH-) – solution
with more OH- than H+. Becomes
basic (alkaline).
2. Hydronium ion (H+) –
solution with more H+ than OH-.
Becomes acidic.
pH scale
blood
0
2
Acidic HCl
7
8
neutral (H20)
ammonia
11
14
basic
** each increase in pH scale # is
10x greater than the # before. 4
is 100x more acidic than 6.
• Buffers – neutralize acids or
bases. Ex. Tums, rolaids