periodicity

Question 1

define periodicity

Answer 1

repeating pattern of physical/chemical properties

across periods

Question 2

what is the trend in atomic radius across period 1+2

Answer 2

decrease left to right
increasing no. of protons
increased positive charge electrons in same shell with similar shielding

Question 3

describe the general trend in 1st ionisation energy

Answer 3

general trend to increase
as increasing no. of protons
as electrons are added to same shell

Question 4

why is there a small drop between Mg + Al/

Answer 4

Mg outer electrons in 3s but Al starting to fill 3p subshell
3p subshell higher in energy than 3s
so electron is easier to remove

Question 5

why is there a small drop between P and S

Answer 5

S outer electron is paired in 3s subshell
negative charges of electrons causes repulsion
so easier to remove electron

Question 6

trend in melting + boiling point for Na, Mg, Al

Answer 6

metallic - strong bonding
gets stronger as more electrons in outer shell are released to sea of electrons
smaller size ion with greater positive charge also makes bonding stronger
high energy needed to break bonds

Question 7

trend in melting + boiling point for Si

Answer 7

macromolecular
many strong covalent bonds between atoms
high energy needed to break covalent bonds
very high mp + bp

Question 8

trend in melting + boiling point for CL2, S8 and P4

Answer 8

simple molecular
weak van der waals between molecules
little energy to break
low mp + bp

Question 9

why does S8 have higher mp than P4

Answer 9

has more electrons

so stronger v der waals between molecules

Question 10

trend in melting + boiling point for Ar

Answer 10

monoatomic

weak van der waals between atoms