3.1 the periodic table

Question 1

state two similarities of elements in the same group

Answer 1

• similar chemical properties

* similar outer shell configuration

Question 2

periodicity is…

Answer 2

a repeating pattern across different periods

Question 3

define first ionisation energy

Answer 3

the energy needed to remove one mole of electron from one mole of gaseous atom to form one mole of gaseous +1 ion

Question 4

define second ionisation energy

Answer 4

the energy needed to remove one mole of electron from one mole of gaseous +1 ion to form one mole of gaseous +2 ion

Question 5

give the equation for the first ionisation energy of mg

Answer 5

mg(g) —> mg+1(g) + e-

Question 6

give the equation for the second ionisation energy of mg

Answer 6

mg+1(g) —> mg+2(g) + e-

Question 7

name three factors that affect ionisation energy

Answer 7

• the attraction of the nucleus (nuclear charge)
• distance from nucleus
• shielding

Question 8

helium has the largest first ionisation energy because….

Answer 8

there is no shielding but has more protons than H so more nuclear charge and stronger attraction to nucleus

Question 9

why do ionisation energies decrease down a group

Answer 9

shielding increases down the group so there is less attraction to the nucleus so outer electrons are lost more easily

Question 10

state and explain the general trend of ionisation energies across a period

Answer 10

increase of ionisation energy, protons increase therefore nuclear charge increases but shielding stays the same but size of atom decreases so attraction of outer electrons to nucleus increases

Question 11

explain the dip in ionisation energies across a period from group 2 to 3

Answer 11

nuclear charge increases as protons increase, outer electrons in group 2 are in s orbital but in group 3 they are in p orbital which is higher in energy so ionisation energy decreases

Question 12

explain the dip in ionisation energies across a period from group 5 to 6

Answer 12

in group 6 the electrons have begun pairing up which causes inorbital repulsion which decreases ionisation energy

Question 13

state and explain in atomic radii across a period

Answer 13

decrease in atomic radii, shielding stays the same, protons increase therefore nuclear charge increases so there is more attraction between electrons and nucleus so shells are pulled inward

Question 14

state and explain the trend of electronegativity across a period

Answer 14

number of protons increase so nuclear charge increases, size of atom decreases so there is stronger attraction from nucleus to the two electrons in a covalent bond

Question 15

explain the trend in melting and boiling points across a period

Answer 15

metals- high, strong metallic bonds, size of ion decreases across the period so sea of free electrons increases
giant covalent- v high, strong covalent bonds lots of energy needed to break
simple molecular- low, weak london forces between molecules, the more e- the stronger forces
monatomic- v low, weak london forces between atoms