Periodicity

Question 1

describe the atomic radius across the period

Answer 1

atomic radius decreases across the period

Question 2

explain why the atomic radius decreases across the period

Answer 2

the nuclear pull increases (more protons). the outer electrons are more strongly attracted, so atoms are drawn in. shielding is similar.

Question 3

define first ionisation energy

Answer 3

the amount of energy required to remove 1 electron from 1 atom of gaseous atoms to form 1+ ions

Question 4

describe the first ionisation energy across the period

Answer 4

ionisation energy increases across the period

Question 5

explain why ionisation energy increases across the period

Answer 5

there are more protons, meaning more nuclear pull, the outer electrons are held more strongly, so are more difficult to remove.

Question 6

describe the melting points across the period

Answer 6

general decrease

Question 7

define electronegativity

Answer 7

the ability of an atom to draw a pair of electrons towards itself within a covalent bond

Question 8

describe the electronegativity within a period

Answer 8

it increases across the period

Question 9

explain the electronegativity across the period

Answer 9

as the nuclear pull increases, the outer electrons are held more strongly including the bonded ones

Question 10

define periodicity

Answer 10

patterns or trends across a period which are repeated in other periods

Question 11

describe the conductivity across the period

Answer 11

general decrease

Question 12

explain the conductivity across the period

Answer 12

Na to Mg increase in conductivity as they are metallically bonded so conduct more delocalised electrons.

Question 13

what is the meaning of the term first ionisation energy

Answer 13

the amount of energy required to remove one electron from one atom of gaseous atoms to form 1+ ions

Question 14

explain the melting points across a period

Answer 14

Na to Mg increase as they are metallically bonded, so are stronger.
Silicon has the highest melting point as it forms a macromolecule, so requires a lot of energy to break bonds. P to Cl decrease as melting point is dependent on the size of the molecule and the resulting Van Der Waals force. S highest, P lower, Cl lowest. Argon has the lowest melting point as it is monatomic, so there are less intermolecular forces, require a lot less energy to break.