1: Fundamental Chemistry

Question 1

atomic structure

Answer 1

same number protons and electrons
atomic number = number of protons
atomic mass = number or protons and neutrons
isotopes = same element with different number of electrons = changed atomic mass

Question 2

carbon dating

Answer 2

fixed amount of carbon left when something dies = determine age of organic artefacts using half life

Question 3

octet rule

Answer 3

atoms most stable when their outer shell full
electrons held in place by electrostatic attractions
noble gases inert
ions = when atoms gain or lose electrons changing their charge
molecules = two or more atoms bonded

Question 4

chemical bonds

Answer 4

ionic = electrons transfer = metal and non-metal = giant lattices = strong bonds
covalent = sharing electrons = two non-metals = weaker bonds
metallic = share a sea of delocalised electrons = two metals

Question 5

shape of molecule

Answer 5

4 orbitals
s = contain up to 2 electrons, spherically symmetric around nucleus
p = contain up to 6 electrons, like two balloon shapes either side nucleus
d = contains up to 10 electrons
f = contains up to 14 electrons
electron pairs want to be as far away from each other as possible as clouds repel
lone pairs have more repulsion

Question 6

polarisation

Answer 6

electronegativity (EN) = a measure of the ability of an atom that is bonded to another atom to attract electrons to itself
increase in electronegativity left to right across period table because nucleus gains more protons which increases pull
decrease in electronegativity down the periodic table because shells get further from nucleus
use delta negative and positive on covalent bonds to show polarity
change in EN less than 0.5 = non-polar covalent bond
change in EN more than 0.5 = polar covalent
change greater than 2 = an ionic bond = permanent change
dipole = separation of charge between two atoms which determines the position of electrons
linear molecules can cancel out their dipole charges to become non-polar
polar molecules more soluble in water

Question 7

intermolecular forces

Answer 7

intramolecular forces = within molecule
intermolecular = between molecules
driven by polarisation

Question 8

London dispersion forces

Answer 8

all atoms and molecules exhibit london dispersion forces between themselves
cloud of negative charge from orbiting electrons
weak forces

Question 9

dipole-dipole atrractions

Answer 9

temporary interaction between positive end on one polar molecule and negative end of another

Question 10

hydrogen bonding

Answer 10

hydrogen bonds to fluorine, nitrogen or oxygen

Question 11

hydroxyl group

Answer 11

oxygen bonded to a hydrogen and another organic molecule (commonly carbon)
called alcohols

Question 12

amine group

Answer 12

nitrogen atom with lone pair of electrons
can be primary, secondary or tertiary depending on what else it’s bonded too

Question 13

carbonyl groups

Answer 13

carbon double bonded to oxygen and two side chains
aldehyde: bonds with hydrogen and another atom
ketone: bonds with two non hydrogen atoms (R)
carboxylic acid: bonds with an OH and another atom
esters: bonds with OR and R
amides: bonds with NH2 and R

Question 14

pH

Answer 14

more hydrogen ions make solution more acidic
1-14
1 = acid
14 = alkaline

Question 15

the mole

Answer 15

1 mole = 6.02 x 10^23 particles (avogadro’s constant)
1 mole = its molecular weight
mass = molecular weight/number of moles