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GRADE 12 CHEMISTRY Cheat Sheet by

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Chapter 1

Chemistry- study of physical properties of matter
matter - anything that has mass or takes up space
Areas of chemistry - organic, inorganic, bioche­­mi­stry, analyt­­ical, and physical
organic chemistry - study of chemicals containing carbon
inorganic chemistry - study of chemicals not containing carbon
bioche­mistry - study of processes taking place in organisms
analytical chemistry - study of compos­ition of matter
physical chemistry - study of the mechanism, rate, and energy transfer that occurs when matter changes

Chapter 1

pure - pursuit of knowledge for itself
applied - research directed to a specific goal
macros­copic - visible to human eye
micros­copic - only visible with microscope
Antoine Lavoisier - made chemistry become a measur­able, observable science
scientific method - observe, test hypoth­esis, and develop theories
hypothesis - proposed explan­ation
experiment - test a hypothesis

Chapter 1

pure - pursuit of knowledge for itself
applied - research directed to a specific goal
macros­copic - visible to human eye
micros­copic - only visible with microscope
Antoine Lavoisier - made chemistry become a measur­able, observable science
scientific method - observe, test hypoth­esis, and develop theories
hypothesis - proposed explan­ation
experiment - test a hypothesis
manipu­lated variable - variable changed intent­ionally during experiment
responding variable - variable observed
theory - well tested explan­ation for a broad set of observ­ations
scientific law - concise statement that summarises results of of observ­ations and experi­ments

Chapter 2

extensive property - property depending on amount of matter in sample
intensive property - property depending on type of matter in sample
mass - a measure of amount matter (SI unit = kg)
volume - a measure of space occupied by matter
physical property - a substance that a person can measure without changing the material
physical change - properties of a material change, but not compos­ition
vapour - a gas state of substance that is liquid or solid at room temp
Solids - fixed volume, fixed shape, close particles
Liquids - free shape, fixed volume, medium particle space
Gas - free shape, easy to compress, far particles
 

Chapter 3

Addition and Subtra­ction of Sig Figs - round to the same number of decimal places as the measur­ement with the least number of decimal places
Multip­lic­ation and Division - round answer to the same number of sig figs as the measur­ement with the least amount of sig figs
12.345 + 6.1 = 18.4
(1.502­)(3.8) = 5.7076 = 5.7

Chapter 3

measur­ement - a quantity that has both a number and a unit
scientific notation - a number written as product of 2 numbers: a coeffi­cient and 10/E to raised to a power, coeffi­cient must be b/w 1 and 10 --- 6.789 x 1025
accuracy a measur­ement of how close a measur­ement comes to the actual­/true
precision - a measure of how close a series of measur­ement are to each other
sig figs - in measur­ement includes all digits that are known plus an estimated digit
Error = Experi­mental Value - Accepted Value
% = | error | / accepted value x 100%

Chapter 3

density -intensive property b/c it has to do with type of substance, not amount and density decreases with increasing temper­atures
density = mas/ volume in g/cm3

Chapter 2

reactant - substance present at start of chemical reaction
product - substance present at end of chemical reaction
partic­ipate - a solid that forms and settles out of liquid mixture
Conser­vation of Mass - in any physic­al/­che­mical reaction, the mass of reactants must = the mass of the products ---- (10g H2 + 8g O2 = 18 H2O)
Clues that a chemical change has ocurred:
- transfer energy
- color change
- production of gas
- partic­ipate forms

Chapter 3

temper­ature - kelvin (0C = 273 K)
units of energy - is measured in calories or joules (joules is SI)
conversion factor - ratio of equivalent measur­ement
dimens­ional analysis - way to solve problems using units, dimens­ions, or measur­ements
5 Base of SI
meter = length
kilograms = mass
kelvin = temper­ature
second = time
mole = number of molecules
litre = volume
1 J = 0.2390 cal
1 cal = 4.184 Joules
mole = number of molecules
litre = volume

Converting - 8.351 g to mg
smaller = multiply
bigger = divide
 

Chapter 4

Atom - smallest particle of element that retains it identity in a chemical reaction
Subatomic particles - protons, neutrons, electrons
Electrons - negatively charged, located outside the nucleus, tiny (9.11 x10-24g), discovered by J.J. Thompson
Protons - positively charged, located in the nucleus, large in comparison to electrons (1.67x10-24), discovered by Eugen Goldstein
Neutrons - no charge, in nucleus, same mass as protons, discovered by James Chadwick
Cathode Rays -the high-speed electrons emitted in a stream from the heated cathode of a vacuum tube
J.J. Thompson's Plum Pudding Model - atoms were positively charged masses with negatively charged electrons distri­buted throughout the mass.
Ruther­ford's Atomic Model/­Theory - The atom is mostly empty space, there is small negatively charged nucleus, electrons are located outside of and around nucleus
Democritus believed atoms were indivi­sible and indest­ruc­tible.

Chapter 2

substance - uniform and definite compos­ition of matter
mixture - a physical blend of 2+ components (can be homoge­neous or hetero­gen­eous)
hetero­geneous - mixture not uniform throughout
homoge­neous - mixture uniform throughout
phase - any part of a solution that is uniform throughout
filtration - process separates a solid from liquid in hetero mix
distil­lation - separates dissolved solids from liquid, which is boiled to produce vapour that has condensed into liquid

Sig Fig Rules

1. every non zero digit is signif­icant
4. zeros at end of number and right of a decimal are signif­icant
2. zeros b/w non zero digits are signif­icant
5. zeros on right end of measur­ement that lie left of a decimal are not signif­icant
3. zeros appearing in front of non zeros (place holders) are not signif­icant
6. there are unlimited sig figs if: you are counting or situations involving exactly defined quantities

Chapter 4

Daltons' Atomic Theory
1. all elements are composed of tiny indivi­sible particles called atoms
2. atoms of same element are identical, atoms of any one element are different from those of another element
3.atoms of different elements can mix together or chemically combine in simple whole number ratios
4. chemical reactions occur when atoms are separated, joined, or arranged. atoms of one element are never changed into atoms of another element.
 

Summary of Principle Energy Levels, and, Orbitals

Principle Energy Level
Number of Sublevels
Type of Sublevels
n = 1
1
1s (1 orbital)
n = 2
2
2s (1 orbital), 2p (3 orbital)
n = 3
3
3s (1 orbital), 3p (3 orbital), 3d (5 orbital)
n = 4
4
4s (1 orbital), 4p (3 orbital), 4d (5 orbital), 4f (7 orbital)

Chapter 4

Atomic Number - number of protons in nucleus in atom
Mass Number - protons + neutrons = total mass #
# neutrons = atomic # - mass#

Maximum Numbers of Electr­ons

Energy Level N
Maximum Number of Electrons
1
2
2
8
3
18
4
32

Chapter 2

element - simplest form of matter that has unique properties
compound - substance containing 2+ elements in fixed proportion
Compounds can be broken down, but elements cannot.
Scientists use chemical symbols to represent elements.
Chemical symbols are always 1 or 2 letters with first letter capita­lized

Chapter 5

Quantum of Energy - is amount of energy required to move an electron from one energy level to another
Orbit - each is associated with an energy level. The orbit an electron is in, determines energy of electron. Electrons can change orbits by gaining or losing energy
Aufbau Principle - electrons occupy orbitals of lowest energy first
*Electron Config­uration - ways electron are arranged in various orbitals
Pauli Exclusion Principle - atomic orbital can hold at most 2 electrons with opposite spin direction ↑↓
Hunds Rule - electrons occupy orbitals of same energy in way that makes # of electrons w/ same spin direction as large as possible

Chapter 4

Atomic Number - number of protons in nucleus in atom
Mass Number - protons + neutrons = total mass # (total # of of protons in nucleus of an element)
# neutrons = atomic # - mass#
isotopes - atoms same element that have same atomic number, but different atomic masses due to difference of neutrons
atomic mass - a unit of mass to = 1/12 the mass of a carbon 12 atom
period - horizontal row of elements in periodic table
group - vertical column of elements in periodic table
 

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