Periodicity + Amounts of substance

Question 1

What force holds the protons and neutrons

Answer 1

strong nuclear force

Question 1

what holds electrons and protons together in an atom

Answer 1

electrostatic forces of attraction

Question 2

why is the nuclear force stronger than an electrostatic force

Answer 2

it overcomes repulsion between protons in nucleus

Question 3

what decides the chemical properties of an element

Answer 3

the number and arrangement of electrons

Question 4

why do isotopes have the same chemical properties

Answer 4

they have the same electron configuration

Question 5

why do electrons fill orbitals singly before they start sharing

Answer 5

electrons repel eachother

Question 6

name 2 transition metals with with unusual electron configurations

Answer 6

1. copper Cu
2. chromium Cr
   they donate 1 of their 4s electrons to 3d sub-shell to make it full

Question 7

what bonds form between group 4-7

Answer 7

covalent bonds to share electrons

Question 8

why are the gases in group 0 enert

Answer 8

they have completely full s and p sub-shells

Question 9

what type of process is ionisation

Answer 9

endothermic, you have to put energy in to ionise atom/molecule

Question 10

name 3 factors that affect ionisation energy

Answer 10

1. nuclear charge
2. shielding
3. distance from nucleus (atomic radius)

Question 11

define ionic bonding

Answer 11

electrostatic forces of attraction between oppositely charged ions in an ionic lattice
chemical link between metal and non-metal

Question 12

define covalent bonding

Answer 12

electrostatic forces of attraction between 2 nuclei and shared pair of electrons
between non-metals

Question 13

define metalic bonding

Answer 13

electrostatic forces of attraction between delocalised electrons and positive ions in metallic lattice

Question 14

which of Na+ and Mg2+ is the smaller ion and why

Answer 14

Mg2+
has more protons with the same amount of shielding

Question 15

explain why ionisation energy decreases down a group

Answer 15

1. atomic radius increases = electrons are further from nucleus
2. more shielding = weaker nuclear attraction

Question 16

explain why ionisation energy increases across a period

Answer 16

1. number of protons increases = stronger nuclear attraction
2. more electrons in the same amount of shielding

Question 17

compare ionisation energy of group 2 and 3

Answer 17

1. Aluminium’s outer electron = in 3p orbital rather than 3s
2. 3p orbital = higher energy level than 3s orbital
3. electron is found further from nucleus
4. 3p orbital has more shielding provided by 3s2 electrons
5. ionisation energy drops slightly, easier to remove electron

Question 18

compare ionisation energy of group 5 and 6

Answer 18

(Shielding identical in phosphorus & sulfur atoms + electron is being removed from an identical orbital)
1. In phosphorus: electron being removed from singly-occupied orbital (3p3)
2. But in sulfur: electron removed from paired electrons in 3p orbital
3. Electron repulsion between 2 electrons = electron easier to remove from pair

Question 19

how to write first ionisation energy

Answer 19

X(g) –> X+(g) + e-

Question 20

define electronegativity

Answer 20

a measure of the tendency of an atom to attract a bonding pair of electrons
fluorine is most electronegative

Question 21

what is avogadro’s constant

Answer 21

6.022 x 10^23

Question 22

what is the conversion of 1 litre to dm3

Answer 22

1 l = 1 dm3

Question 23

equation for concentration

Answer 23

n = c x v

Question 24

unit for molarity

Answer 24

mol/l mol/dm3 M

Question 25

what are intra and inter molecular bonds

Answer 25

intramolecular bonds - act within a molecule intermoleculer bonds - act between molecules

Question 26

properties of ionic compounds

Answer 26

1. high melting and boiling points 2. water soluble

Question 27

what type of bonds are single and double bonds

Answer 27

single bond = sigma bond double bond = pi bond

Question 28

properties of covalent bonds

Answer 28

1. low melting and boiling points

Question 29

define coordinate bond

Answer 29

covalent link between two atoms, but both of the shared electrons come from one of the bonding pairs

Question 30

what are the 3 main types of intermolecular bonds in order of strength

Answer 30

1. van del waals 2. dipole-dipole 3. hydrogen bonds

Question 31

what are van der waals forces

Answer 31

an instantaneous slight negative charge when electrons briefly bunch together at one side of the atom

Question 32

what are dipole-dipole forces

Answer 32

* when electrons in a polar molecule are pulled towards the more electronegative atom * causing a slight negative charge at one end and a slight positive charge at the other end

Question 33

what are hydorgen bonds

Answer 33

a weak electrostatic attraction between polar molecules which occurs when a hydrogen atom binds to a lone pair of electron on a highly electronegative atom h-bonds between only NOF