3.7

Question 1

what is the atomic radius of an atom

Answer 1

the distance between the nucleus of two atoms in a pure element

Question 2

what causes the decrease in size across a period

Answer 2

increase in effective nuclear charge

Question 3

why do noble gases not have an atomic radius and how are they measured

Answer 3

they don’t form covalent bonds and they use van der waals radii

Question 4

how is the ionic radius found

Answer 4

the internuclear distance in ionic solids

Question 5

define ionisation energy

Answer 5

energy change when an electron is removed from an atom of the element in the gas phase

Question 6

what units are for ionisation energy usually

Answer 6

kjmol-1

Question 7

do endothermic processes have positive or negative values

Answer 7

positive

Question 8

why does ionisation energy increase across a period apart from between the second and third group and fifth and sixth group

Answer 8

because of increased effective nuclear charge but between the s and p shell it reduces because p is at a higher energy level
between fifth and sixth group the electron being removed is in a pair so there is extra repulsion

Question 9

what is electron gain energy

Answer 9

energy change that occurs when an electron is attached to an atom in the gas phase

Question 10

is adding electrons to an atom an endo or exothermic process

Answer 10

it can be either

Question 11

is ionisation energy endo or exo thermic

Answer 11

endothermic

Question 12

are second and up electron gain energies endo or exothermic

Answer 12

endothermic