Chapter 7 periodicity

Question 1

Describe the periodic table Mendeleev created

Answer 1

• arranged in order of atomic mass
• He lines elements in groups with similar properties
• if the elements did not fit the similar properties he would switch them and leave gasp

Question 2

Describe the modern periodic table

Answer 2

• from left to right elements are arranged in order of increasing atom number
• each successive element has atoms with one extra proton

Question 3

What are groups

Answer 3

• vertical columns
• each element in group has atoms with the same number of outer shell electrons
• similar properties

Question 4

What are periods

Answer 4

• horizontal rows
• the highest energy electron shell in an element’s atom

Question 5

What is periodicity

Answer 5

the repeating trend in properties of the elements

Question 6

What is the s block

Answer 6

highest energy electron in an s orbital

Question 7

What is an element in the p block

Answer 7

highest energy electron in the p orbital

Question 8

What is ionisation energy

Answer 8

• how easily an atom loses electrons to form a positive ion

Question 9

What is the first ionisation energy

Answer 9

• the energy required to remove one electron from each atom in one mole of gasours atoms of an element to form one mole of gaseous 1+ ions

Question 10

What factors affet ionisation energy

Answer 10

• atomic radius
• nuclear charge
• electron shielding

Question 11

How does atomic radius affect ionisation energy

Answer 11

• the greater the distance between nucleus and outer electrons with the less nuclear attraction
• the force of attraction falls with increasing distance

Question 12

How does nuclear charge affect ionisation energy

Answer 12

• the more protons there are in the nucleus of an atom the greater the attraction between nucleus and outer electrons

Question 13

How does electron shielding affect ionisation energy

Answer 13

• electrons are negativley charges so inner shell electrons repel outer shell electrons
• the repulsion is shielding reducing the attraction betwene nucleus and outer electrons

Question 14

How do you know how many successive ionisation energies an element has

Answer 14

• same number as electrons

Question 15

Describe the second ionisation energy in helium

Answer 15

• greater than the first ionisation energy
• two protons attracting two electrons in te 1s sub shell
• after first electron lost single electron puller closer to the nucleus
• nuclear attraction incresases so more ionisation energy needed to remove this second electron

Question 16

What is the second ionisation energy

Answer 16

• is the energy required to remove one electron from each ion in one mole of gaseous 1+ ions of an element to form one mole of gaseous 2+ ions

Question 17

How do you predict ionisation energies from a table

Answer 17

• see where the largest jump is in ioisation eergies
• the amount of ionisation energies till the jump is the number of electrons in its outer shell
• therfore you can see the group of the element

Question 18

Describe the successive ionisation energies in a graph

Answer 18

• large jumps are change in shells
• small jumps are change in sub shells

Question 19

Describe the two key patterns in the first 20 key elements in ionisation energy in a periodic table

Answer 19

• general increase in first ionisation energy across each period (H-> He, LI-> Ne, Na-Ar)
• a sharp decrease in first ionidation energy between the end of one period and the start of the next period (He-> Li, Ne-Na, Ar->K)

Question 20

Decribe the trend on ionisation energy down a group

Answer 20

• atomic raidus increases
• more inner shells so shieldong increases
• nucelar attraction on outer electrons decreases
• first ionisation energy decreases

Question 21

Describe the trend of first ionisation energy across a period

Answer 21

• nuclear charge increases
• same shell similar shielding
• nuclear attraction increases
• atomic radius decreases
• first ionisation energy increases

Question 22

Compare the ionisation energy between beyillum and boron

Answer 22

• the 2p sub shell in boron has a higher energy than the 2s sub shell in beryillium
• ttherefore boron the 2p electron is easieer to remove than one of the 2 electrons in beryllium
• the first ionisation energy of boron is less that the frist ionisation energy of beryllium

Question 23

Compare the ionisation energy between nitrogen and oxygen

Answer 23

• in nitrogen and oxygen the highest energy electrons are in 2p sub shells
• in pxygen paired elecrons in one of the 2p orbitals repel one another making it easier to remove en electron from an oxygen atom than a nitrogen atom
• therefore the first ionisation energu of oxygen is less than the first ionisation energy of nitrogen

Question 24

Describe the structure of metals

Answer 24

• in a solid structure each ato has donated its negative outer shell electrons to a shared poll of electrons delocalised throughout whole structure
• positvie ions left behind consist of nucleus and the inner electron shells of metal atoms
• cations are fixed in positions maintaining structure
• delicalised electrons are movile and are able to move throughout the structure

Question 25

What is metallic bonding

Answer 25

* strong electrostatic attraction between cations and delocalised electrons

Question 26

What is the main structure of metals

Answer 26

giant metallic lattice

Question 27

Why can metals conduct electricity

Answer 27

* can conduct in solid and liquid stated * delocalise electrons can move throught structue carrying charge

Question 28

Descrube why metals have high melting and boiling points

Answer 28

* large amount of energy needed to overcome the strong electrostatic attraction between cations and electrons * higher in those whose electrostatic charge is larger because they have a larger charge on atom which makes them smaller and more delocalised electrons

Question 29

Describe the solubulity of metals

Answer 29

* they do not dissolve

Question 30

Describe giant covalent structures and what elements have these structures

Answer 30

* boron ,carbon and silicon * instead of small molecules and intemolecular forces billions of atoms held with strong covalent bonds to from a giant covalent lattice * carbon and silicon bond to other carbon and silicon atoms forming a tetrahedral structure

Question 31

Describe the structure of diamond

Answer 31

* tetrahedral arrangment * bond angles are 109.5 by electron pair repulsion

Question 32

What are the melting and boiling like of giant covalent structures

Answer 32

* high melting and boiling points * covalent bonds are strong * large quantity of energy to break strong covalent bonds

Question 33

Describe the solubility of giant covalent structures

Answer 33

* insoluble * covalent bonds holding together atoms in the lattice are far too strong to be broken by interactin with solvents

Question 34

Describe the electrical conductivity of giant covalent structures

Answer 34

* non conductors of electricity * except graphene and graphite - they only form 3 covalent bonds so one atom is delocalised which can carry a charge round structure

Question 35

Describe the trends in metling and boiling point in period 2

Answer 35

* Li-Be - giant metallic lattice - strong metallic bonds between cations and delocalised electrons * B-C - giant covalent structures -strong covalent bonds between atoms * N2-Ne - simple molecular structure 0 weak london forces between molecules

Question 36

Describe the trend in in melting and boiling points in period 3

Answer 36

* Na-Al- - giant metallic lattice - strong metallic bonds between cations and delocalised electrons * Si- giant covalent structures -strong covalent bonds between atoms * P4,S8,Cl2,Ar - simple molecular structure 0 weak london forces between molecules