Periodicity

Question 1

periodicity

Answer 1

• within period same number of electron shells

- repeating trends in physical and chemical properties of elements across each period

Question 2

chemical properties

Answer 2

• elements within a group same number of electrons in outer shell
• so same chemical properties

Question 3

electronic configuration

Answer 3

• decides chemical properties of an element
• S block = 1 or 2 outer shell electrons easily lost to form positive ions with an inert gas configuration
• group 5,6 +7 = gain electrons to form negative ions with an inert gas configuration
• group 4-7 can share electrons when forming covalent bonds
• group 0 = completely filled s+p subshells so inert

Question 4

inert

Answer 4

-not generally reactive

Question 5

atomic radius

Answer 5

• decreases across period
• number of protons increase so positive charge of nucleus increases
• electrons pulled closer to nucleus making atomic radius smaller
• extra electrons elements gain across period are added to outer energy level so don’t provide extra shielding

Question 6

Ionisation energy

Answer 6

• increases across a period
• number of protons increase so stronger nuclear attraction
• extra electrons are at roughly same energy levels even if outer electrons are in a different orbital types
• little extra shielding effect or extra distance to lesson attraction from nucleus

Question 7

Drop Between groups 2+3

Answer 7

• shows subshell structure
• Al outer electron is in a 3p orbital rather than 3s
• 3p slightly higher energy so electron is found further from nucleus
• 3p additional shielding provided by 3s2 electrons
• these factors together are strong enough to override the effect of increased nuclear charge
• so ionisation energy groups slightly providing evidence of electron subshells

Question 8

drop between group 5+6

Answer 8

• shielding identical in phosphorus and sulfur atoms and electron being removed from an identical orbital
• phosphorus electrons are removed from singly occupied orbital
• sulfur electrons are being removed from an orbital containing 2 electrons
• so repulsion between 2 electrons
• easier to remove from shared orbital

Question 9

melting and boiling points

Answer 9

-affected by bond strength across a period

Question 10

metals

Answer 10

• mp and bp increase across period because metallic bonds get stronger
• metal ion increasing number of delocalised electrons and a decreasing a radius
• stronger attraction between metal ions and delocalised electrons’ this is the stronger metallic bonding

Question 11

giant covalent lattice structures

Answer 11

• strong covalent bonds linking all atoms together
• a lot of energy needed to break bonds
• highest boiling point in period

Question 12

-simple molecular structures

Answer 12

• mp depends upon strenght of london forced between molecules
• london forces are weak and easily overcome so low mp and bp

Question 13

more electrons in molecule

Answer 13

• stronger london forces

- sulfur has most electrons in period 3 so has the higher mp and bp then phosphorus and chlorine

Question 14

noble gases

Answer 14

• lowest mp and bp in their periods
• exsist as individual atoms (monatomic)
• resulting in very weak london forces