unit 3 - chem math Flashcards
1
Q
mole
A
- a mole represents a number
- 1 mole = 6.02 x 10^23
2
Q
mass of an atom is in
A
AMU
3
Q
mass of a mole of atoms is in
A
grams
4
Q
when converting moles to anything
A
MOLEtiply
5
Q
when converting TO moles
A
divide
6
Q
gram formula mass
A
- mass of 1 mole
- the mass of a substance expressed in grams instead of AMU
7
Q
molar mass
A
gfm
8
Q
% composition
A
the amount of an element in a compound expressed as a %
9
Q
hydrate
A
is a salt that has a definite amount of water molecules embedded into its structure
10
Q
anhydrous salt
A
what we are left with after heating a hydrate and the water evaporates
11
Q
molecular formula
A
- true formula for a compound
- exact number of atoms of each element in the compound
12
Q
empirical formula
A
simplest whole # ratio of compound
13
Q
to find the ratio of molecular to empirical…
A
molecular mass/empirical mass
14
Q
1 mole of any gas occupies
A
22.4 liters at STP
15
Q
stoichiometry
A
the area of chem math where we take a balanced chemical equation to use mole ratios (coefficients) to make predictions about the products of the reaction
16
Q
1 step stoichiometry problems are
A
- mole to mole
- liter to liter
17
Q
limiting reagent problems
A
a reactant is in short supply
18
Q
hint about determine LR problems
A
LR problems will give you the masses of each reactant
19
Q
elements
A
made of one kind of atom
20
Q
compound
A
substance made of two or more elements that are chemically combined
21
Q
ionic compounds
A
form between positive and negative ions
22
Q
when do u use roman numerals
A
always use a roman numeral to designate the charge on metals with multiple oxidation states
23
Q
molecules
A
made of 2 NON METALS held together by covalent bonds
24
Q
covalent bonds prefix vowel rule
A
drop the o or a in the prefix name if the element begins with a vowel
25
ammonia
NH3
26
hydrogen peroxide
H2O2
27
subscripts
number written below and to the right of a chemical symbol, shows the number of atoms of each element
28
chemical formula
a shorthand notation for a compound or diatomic element
29
chemical equation
a representation of a chemical reaction where the reactants and products are expressed in formulas
30
what is conserved in chemical reactions
mass charge and energy
31
the law of conservation of mass
- mass is neither created nor destroyed in any chemical reaction
- the number of atoms of each element in the reactants must equal the number of atoms of each element in the products
32
combustion
a chemical combines with OXYGEN to produce carbon dioxide and water
33
synthesis
production of a single compound from two or more substances (elements)
34
methane
CH4
35
decomposition
when a single compound breaks down into 2 or more simpler substances
36
single replacement
an element (a) reacts with a compound (bc) to take the place of one of the components of the compound
37
double replacement
two compounds both exchange partners
38
atom
smallest particle of an element
39
atoms are made of 3 subatomic particles
protons, neutrons, electrons
40
nucleon
any particle found in the nucleus (protons and neutrons)
41
all atoms are electrically neutral because…
#electrons = #protons
42
protons
- particles found in the nucleus of an atom
- have a mass of 1 amu
- each have a +1 charge
- number of protons of an atom NEVER change
43
atomic number
the number of protons
44
nuclear charge
the number of protons
45
neutrons
- particles that are located in the nucleus
- have a mass of 1 amu
- neutral charge
46
mass number
the total number of protons and neutrons in an atom (always a whole number)
mass # = P + N
47
electrons
- particles that rotate or revolve around the nucleus
- very small (1/1836 of a proton)
- mass = zero AMU
- charge for each is -1
- electrons are lost and gained in chemical reactions
48
23
Na
11
23 <- mass number (P + N)
Na <- element symbol
11 <- atomic number (=P)
49
S-32 , C-12
32 & 12 are mass numbers
50
ions
atoms with a charge
- #Protons does not equal #Electrons
- amount of positive charge does not equal negative charge
51
isotopes
atoms of the same element that have the same number of protons, BUT a different number of neutrons
- named after their mass number
52
atomic mass
average of the masses of all naturally occurring isotopes of an element
- written as a decimal
- closest to the mass number of the most common isotope
53
john dalton
cannonball model
- believed that atoms were solid with indivisible parts
- atoms were indestructible
- believed that atoms are the basic unit of matter
54
jj thomson
plum pudding model
- discovered electrons using a cathode ray tube
- believed atoms were solid, positive spheres with electrons embedded in it
55
ernest rutherford
nuclear model
- an atom has a positive nucleus at the center, with electrons outside the nucleus
- atom is made up mostly of empty space
56
gold foil experiment
observations:
- most alpha particles went through the gold foil
- occasionally an alpha particle was deflected back
conclusions:
- atom is made up mostly of empty space
- an atom has a positive, dense, nucleus
57
niels bohr
planetary/bohr model
- electrons are arranged in energy levels in orbit around the nucleus
- electrons orbit around the nucleus like planets move around the sun
- electrons revolve around in several concentric rings/shells/PELs
- each ring represents an amount of energy electrons have associated with a definite average distance from the nucleus
58
PEL 1 electron capacity
2
59
PEL 2 electron capacity
8 electrons
60
PEL 3 electron capacity
18 electrons
61
PEL 4 electron capacity
32 electrons
62
modern theory
wave mechanical theory or electron cloud model
- one cannot predict the exact position of an electron in time
- electrons are found in orbitals
63
orbitals
regions of electron probability
64
electronic configuration
# of electrons in each ring around the atom
65
valence electrons
electrons that are in the outermost ring of an atom, involved in bonding
66
ground state
- all the electrons are in the lowest energy orbitals or rings
- this state is the electron configuration given on the periodic table
67
excited state
- an electron has absorbed energy and temporarily moved to a higher energy ring
- unstable condition
68
light produced
- when an electron absorbs energy it jumps away from the nucleus and enters the excited state
- when the electron falls back down to the ground state it releases energy in the form of light
69
spectroscope
an instrument that can separate polychromatic light into the many wavelengths of light that make it up
70
color spectrum of an element is
a unique characteristic and can be used to identify it; it’s a unique fingerprint
71
sublevels
s p d f
72
principle quantum number
determines the number of sublevels within the PEL
73
electron spin
an orbital can hold only two electrons and they must have opposite spin
74
electron configurations w skips
- note that after the 3p sublevel is filled, the 4s is filled than the 3d
- 4s is further from the nucleus BUT electrons in 3d have more energy due to repulsion between electrons
