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A Level Chemistry > Periodicity > Flashcards

Periodicity Flashcards

1
Q

How are elements arranged on the periodic table

A

In order of increasing atomic number

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2
Q

Horizontal rows are called

A

Periods

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3
Q

As you move along a period what happens to each element

A

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

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4
Q

Vertical columns are called what

A

GroupsW

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5
Q

What is special about elements in the same group

A

Have similar chemical properties

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6
Q

How is the periodic table divided in terms of blocks

A

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

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7
Q

What block are groups 1 and 2

A

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

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8
Q

What blocks are groups 3 to 7 and 0

A

P block, electrons are being added to the P subshell

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9
Q

What elements on the Periodic table consist of D block

A

Transition metals

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10
Q

What element on the periodic table are the F blocks

A

Lanthanides and the Actinides

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11
Q

What determines the position and chemical properties of elements

A

Their electronic configuration

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12
Q

How can you predict properties of elements

A

By seeing where they are positioned on the periodic table

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13
Q

Define Periodicity

A

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

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14
Q

What properties display periodicity?

A

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

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15
Q

What is atomic radius?

A

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

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16
Q

How can you calculate atomic radii

A

Covalent radii
Metallic Radii

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17
Q

How do you calculate atomic radii using Covalent radii?

A

-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

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18
Q

How do you calculate atomic radii using Metallic radii?

A

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

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19
Q

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

A

Decreases

20
Q

Why does atomic radii decrease across a period?

A

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)
21
Q

Define First Ionization energy.

A

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.

22
Q

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

A

Increases

23
Q

Why does Ionization energy increase across period 3?

A

-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

24
Q

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

A

-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

25
Q

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

A
  • 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

26
Q

Define Electronegativity.

A

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

27
Q

The more electronegative an atom is…

A

…The more strongly it pulls electrons towards itself

28
Q

What can electronegativity be used to predict?

A

The polarity of a covalent bond

29
Q

First ionization energy is…

A

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

30
Q

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

A

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

31
Q

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

A

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

32
Q

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

A

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

33
Q

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

A

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

34
Q

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

A
  • 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

35
Q

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

A

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

36
Q

Describe the trend across a period

A

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

37
Q

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

A

As we move down a group the atoms become larger

38
Q

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

A

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

39
Q

What happens to electron shielding as move down a group?

A

Number of electron shells increases so amount of electron shielding increases

40
Q

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

A

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

41
Q

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

A

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

42
Q

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

A

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

43
Q

What is the trend as we move down any group?

A

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

44
Q

Why are ionization values always positive?

A

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

45
Q

What is successive ionization energy/ second ionization energy?

A
46
Q
A

A Level Chemistry (10 decks)

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