periodic table and energy

Question 1

what is periodicity

Answer 1

the repeating pattern of behaviour across a period

Question 2

how is the periodic table arrnaged

Answer 2

in order of increasing atomic number

Question 3

elements in the same group have similar _______

Answer 3

chemical properties

Question 4

what is the definition for first ionisation energy

Answer 4

the energy recquired to remove one mole of electrons from one mole of gaseous atoms to form one mole of gaseous ions with a 1+ charge

Question 5

what is meant by atomic radius

Answer 5

the distance between the nucleus and the electron being removed

Question 6

what is meant by nuclear charge

Answer 6

the number of protons in the nucleus

Question 7

what is meant by electron shielding

Answer 7

the amount of shells between the nucleus and the electron being removed

Question 8

what is the trend in ionisation energy across a period

Answer 8

• atomic radius decreases
• electron shielding remains the same
• nuclear charge increases
  therefore nuclear attraction increases- more energy is required to remove the outermost electron

Question 9

what is the trend in ionisation energy down a group

Answer 9

• atomic radius increases
• nuclear charge increases (but this is outweighed)
• electron shielding increases
  therefore nuclear attraction decreases, less energy is required to remove the outermost electron.

Question 10

ionisation energy usually increases across a period, however there is a small decrease between Be and B, explain this.

Answer 10

Be’s outermost electron is in a 2s orbital, B’s outermost electron is in a 2p orbital - which is further away from the nucleus. Therefore B’s outermost electron experiences less nuclear attraction, therefore slightly less energy needs to be put in to remove it.

Question 11

ionisation energy usually increases across a period, however there is a small decrease between N and O, Explain this.

Answer 11

both N and O have their outermost electron in a 2p orbital. However oxygen has 2 electrons paired up in one 2p orbital. Paired electrons in oxygen repel one another, and therefore less energy is required to remove.

Question 12

ionisation energy usually increases across a period, however there is a small decrease in two places, where are these places

Answer 12

between Be and B

between N and O

Question 13

what is metallic bonding

Answer 13

the strong electrostatic attraction between positive metal ions and negative delocalised electrons

Question 14

what are the 3 properties of metals

Answer 14

• conduct electricity - mobile delocalised electrons
• insoluble in water
• strong metallic bonds cause high melting and boiling points

Question 15

what can affect the conductivity of metals

Answer 15

the number of delocalised electrons, the more delocalised electrons, the more conductive.

Question 16

why do successive ionisation energies always increase

Answer 16

• larger ratio of protons to electrons
• atomic radius decreases therefore nuclear attraction increases

Question 17

what is an ionic bond

Answer 17

electrostatic attraction between positively and negatively charged ions

Question 18

what are the 4 giant covelant lattice structures

Answer 18

diamond
graphite
graphene
silicon

Question 19

outline the bonding and properties of diamond

Answer 19

• each carbon atom makes 4 strong covelant bonds to 4 other carbons
• the shape around each carbon is tetrahedral bond angle 109.5
• high melting point - strong covelant bonds
• insoluble in water
• does not conduct electricity- no delocalised electrons, all electrons used in bonding

Question 20

outline the bonding and properties of graphite

Answer 20

• each carbon makes 3 strong covelant bonds to other carbons
• carbons are arranged in a hexagonal arrangment, trigonal planar shape, bond angle 120
• 4th electron is delocalised
• insoluble
• high melting point - strong covelant bonds WITHIN layers
• soft as weak london forces BETWEEN layers
• can conduct electricity due to delocalised electrons

Question 21

outline the bonding and properties of graphene

Answer 21

• each carbon makes 3 bonds to another carbon
• shape is trigonal planar 120 bond angle
  -single layer of graphite
• conducts electricity and heat
• insoluble
• very strong

Question 22

outline the bonding and properties of silicon

Answer 22

• each silicon atom makes four bonds
• tetrahedral shape bond angle 109.5
• high melting point due to strong covelant bonds between atoms
• insoluble
• does not conduct electricity, all outershell electrons used in bonding

Question 23

what are some practical uses of silicon

Answer 23

used in transistors, as pure silicon does not conduct electricity it must be mixed with a small amount of impurities.

Question 24

across periods 2 and 3, list all the elements that create a giant metallic lattice

Answer 24

GROUP 2: Li, Be

GROUP 3: Na, Mg, Al

Question 25

across periods 2 and 3, list all the elements that form a giant covelant lattice

Answer 25

GROUP 2: B and C

GROUP 3: Si

Question 26

across periods 2 and 3, list all the elements that form simple molecular lattices

Answer 26

GROUP 2: N2, O2, F2, Ne

GROUP 3: P, S, Cl2, Ar

Question 27

what affects the metling/boiling point of simple molecular lattices

Answer 27

the number of electrons

london forces increase in strength with an increase in electrons.

Question 28

what is a covelant bond

Answer 28

the bond formed between atoms that share electrons