Periodicity

Question 1

How are elements arranged on the periodic table

Answer 1

In order of increasing atomic number

Question 2

Horizontal rows are called

Answer 2

Periods

Question 3

As you move along a period what happens to each element

Answer 3

Increases by a proton and an electron, hence an increase in atomic number

Question 4

Vertical columns are called what

Answer 4

GroupsW

Question 5

What is special about elements in the same group

Answer 5

Have similar chemical properties

Question 6

How is the periodic table divided in terms of blocks

Answer 6

According to electronic sub-level being filled e.g. S, P, D, F blocks

Question 7

What block are groups 1 and 2

Answer 7

S block, electrons are being added to the S sub-shell

Question 8

What blocks are groups 3 to 7 and 0

Answer 8

P block, electrons are being added to the P subshell

Question 9

What elements on the Periodic table consist of D block

Answer 9

Transition metals

Question 10

What element on the periodic table are the F blocks

Answer 10

Lanthanides and the Actinides

Question 11

What determines the position and chemical properties of elements

Answer 11

Their electronic configuration

Question 12

How can you predict properties of elements

Answer 12

By seeing where they are positioned on the periodic table

Question 13

Define Periodicity

Answer 13

A repeating trend in the properties of elements across each period of the periodic table

Question 14

What properties display periodicity?

Answer 14

-ionization energy
-atomic radius
-melting points
-boiling points

Question 15

What is atomic radius?

Answer 15

Distance from the center of the nucleus to the outermost electrons (valence electrons)

Question 16

How can you calculate atomic radii

Answer 16

Covalent radii
Metallic Radii

Question 17

How do you calculate atomic radii using Covalent radii?

Answer 17

-calculated by measuring distance between two covalently bonded atoms and dividing by two to get individual radii (atoms have to be the same element otherwise their diameters will not be equal

Question 18

How do you calculate atomic radii using Metallic radii?

Answer 18

Metallic radii, calculated by measuring diameter of a cluster of metal atoms and then dividing by the number of atoms

-only works for atoms of the same type

Question 19

As you move across a period what happens to the atomic radii?

Answer 19

Decreases

Question 20

Why does atomic radii decrease across a period?

Answer 20

As you go across a period:

• a proton is added to nucleus= increases nuclear charge= greater pull generated from nucleus to all e-
• Shielding remains constant
• meaning all e- are drawn closer to nucleus
  -T/F less distance between valence e- and center of nucleus (atomic radii)

Question 21

Define First Ionization energy.

Answer 21

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

Question 22

As you move across period 3 what happens to the Ionization energy?

Answer 22

Increases

Question 23

Why does Ionization energy increase across period 3?

Answer 23

-atomic radii decreases
-shielding remains constant
-no. of protons is increasing so positive charge on nucleus increases
-causes electrons to be held more tightly so more energy is needed to release them

Question 24

As you move across period 3 is there a steady increase in IE?

Answer 24

-not a steady rise because of different sublevel
- Na+ Mg= increasing
-DIP at Al
- Al+ Si+ P= increasing
- DIP at S
-S+ Cl +Ar= increasing

Question 25

Why is there not a steady increase in IE as you move across period 3? (5 marks)

Answer 25

- because of different sublevels - First rise= for the s orbital -A dip for Al= electrons are being removed from p orbital where electrons are at higher energies so easier to remove -Next rise= for first 3 electrons of p orbitals where unpaired electrons are being removed - 2nd Dip= when first paired electron is removed in S, there is more electrostatic repulsion between paired electrons so they are easier to remove -Trend then continues to increase as expected due to increase in Nuclear charge

Question 26

Define Electronegativity.

Answer 26

A measure of the attraction of a bonded atom for the pair of electrons in a covalent bond

Question 27

The more electronegative an atom is...

Answer 27

...The more strongly it pulls electrons towards itself

Question 28

What can electronegativity be used to predict?

Answer 28

The polarity of a covalent bond

Question 29

First ionization energy is...

Answer 29

energy needed to remove 1 electron from each atom in 1 mole of gaseous atoms

Question 30

Look at periods 2 and 3 only. What happens to the size of the atoms as we move across a period? Why?

Answer 30

Atoms get smaller across a period: atomic radii decreases -e- shielding remains constant -number of outer shells stays the same -the number of protons increases across a period so the positive nuclear charge increases meaning nuclear attraction increases -as electrons are being held more tightly -decreasing atomic radii- distance between nucleus and valence electrons

Question 31

How will the atomic radius decreasing have an affect on the First Ionization energy?

Answer 31

First IE increases- -atomic radius decreases -electrons are being held more closely to nucleus as nuclear charge increases pulling the electrons -electron shielding stays the same Overall there is an increase to First IE as the tendency to loose electrons on an atom decreases, because more electrons are on the same outer shell and have stronger attraction to nucleus

Question 32

What happens to atomic radius, nuclear charge and electron shielding as we move across period 2 and 3?

Answer 32

Atomic radius= decreases Nuclear charge= Increases Electron shielding= remains constant as electrons are on the same outer shell Overall increase in nuclear attraction as electrons are being held more closely to the nucleus, needing more energy to remove them

Question 33

What happens to electron shielding as we move across a period?

Answer 33

No. of shells present stays the same= electron shielding remains constant

Question 34

Electron shielding remains constant across periods 2 and 3. What affect will this have on strength of attraction between nucleus and valence electrons?

Answer 34

- electron shielding remains constant but nuclear charge increases: -as we move across a period, more protons are being added onto the nucleus of each atom -as we move across a period there are also increasing electrons in each atom -Electrons stay in the same outer shell- these are attracted to the positive nucleus which pulls the valence electrons decreasing atomic radius -over all increase in nuclear attraction

Question 35

What happens to the nuclear charge as we move across a period? How does this effect the first ionization energy?

Answer 35

Number of protons increases as we move across a period, therefore there is a stronger nuclear attraction between electrons and nucleus -This increases the first ionization energy

Question 36

Describe the trend across a period

Answer 36

Number of electrons increases Number of protons increases Nuclear charge increases Atomic radius decreases Electron Shielding remains constant Nuclear attraction increases Increases First Ionization energy

Question 37

What happens to the size of any atoms as we move down a group?

Answer 37

As we move down a group the atoms become larger

Question 38

As we move down a group the atoms become larger. What affect will this have on the first ionization energy?

Answer 38

Atomic radius increases -Distance between valence electrons and nucleus increases, so we need less energy to remove it as nuclear attraction is lost

Question 39

What happens to electron shielding as move down a group?

Answer 39

Number of electron shells increases so amount of electron shielding increases

Question 40

Electron shielding increases down a group, how does this affect the strength of the attraction between valence electrons and nucleus?

Answer 40

-no of shells present increases -electron shielding increases - Nuclear attraction is weakened between valence electrons and positive nucleus due to more shielding

Question 41

What happens to the nuclear charge as we move down a group?

Answer 41

Nuclear charge increases, down a group however its effect is outweighed by increased atomic radius and ( to a lesser extent) electron shielding

Question 42

What has the bigger effect in terms of trends down a group?

Answer 42

-Increasing atomic radii -increasing electron shielding (to a lesser extent)

Question 43

What is the trend as we move down any group?

Answer 43

-atomic radius increases -electron shielding increases -Nuclear charge increases= effect is outweighed by atomic radius -Nuclear attraction on outer electron decreases First IE decreases

Question 44

Why are ionization values always positive?

Answer 44

Because energy must be supplied (an endothermic energy change) to seperate electrons from atoms

Question 45

What is successive ionization energy/ second ionization energy?