Periodicity

S3.1

Name and properties of group 1

Name and properties of group 1

Name: alkali metals

Properties: very reactive, good conductors, low density and shiny grey surfaces

Name and properties of group 2

Name: alkali earth metals

Properties: reactive, good conductors

Name and properties of group 17

Name: halogens

Properties: coloured, go from gas → liquid → solid down the group, very reactive

Name and properties of group 18

Name: noble gases

Properties: non-reactive, stable, monatomic

Name and properties of the d-block

Name: transition metals

Properties: good conductors, malleable, high melting point, high densities

What is the f-block called?

top row: lanthanide

bottom row: actinide

Define metalloids

they have properties of both metals and non-metals: look like metals but have the chemical properties of non-metals

Define atomic radius

the atomic radius is half the distance between an element’s nucleus and the neighbouring nucleus

What are the trends of the atomic radius on the periodic table?

• increases down a group because of the extra filled energy shell

• decreases across a period because the ENC increases. However, this is limited because the more electrons there are in a shell, the more they repel each other

Define ionic radius

the ionic radius is half the distance between an ion’s nucleus and the neighbouring nucleus

What are trends of the ionic radius on the periodic table?

• this increases down a group because of the extra filled energy shell

• this decreases across a period until you get to the anions, here it makes a jump and then decreases again

Define electronegativity

the measure of the ability of an element’s atom to attract electrons in a covalent bond

What are the trends of electronegativity on the periodic table?

• this increases across a period because ENC increases

• This decreases down a group because the nucleus is farther away from bonding electrons due to an extra filled energy shell

define polarity

the larger the difference in electronegativity, the higher the polarity

define ionisation energy

the minimum amount of energy required to remove 1 mole of electrons from 1 mole of gaseous atoms

What are the trends of ionisation energy on the periodic table?

• this increases as you go across a period because ENC increases

• this decreases down a group because the nucleus has less pull on valence electrons due to an extra filled energy shell

define electron affinity

the energy change that occurs when 1 mole of ectrons is added to 1 mole of gaseous atoms

what is the first, second, third electron affinity

first: the first electron added

second: the second electron added

third: the third electron added, etc…

what are the trends of electron affinity on the periodic table?

• this decreases down a group because the nucleus is further from valence electrons

• this increases across a period because ENC increases

define effective nuclear charge (ENC)

the amount of charge valence electrons experience

how do you calculate ENC

ENC = number of valence electrons