Periodicity Flashcards

1
Q

Periodicity

A

Repeating trends of physical or chemical properties

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2
Q

Blocking of the Periodic table

A

The block of an element (s,d,p,f) corresponds to the sub level where the outermost (highest energy) electron is

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3
Q

Trends in atomic radius (Increasing)

A

Atomic Radius INCREASES DOWN a group :

  • There are extra energy levels because there are more electrons
  • More shielding
    Attraction the the nucleus decreases
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4
Q

Trends in atomic radius (Decreasing)

A

Atomic radius DECREASES ACROSS a period:

-Number of protons increases
- Same energy levels
- Similar/Same shielding
- Attraction to the nucleus decreases

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5
Q

First Ionisation energy

A

The energy required to remove 1mol of electrons from 1mol of gaseous atoms

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6
Q

Trend in the 1st IE down group 2

A

-Ionisation Energy decreases
- Extra energy level because more electrons
- More shielding
- Weaker attraction between nucleus and outer electron
- Requires less energy to remove an electron
- The electron is removed from a higher principle energy level

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7
Q

Trend in the 1st IE across period 3 elements

A

The general trend across the period is an increase in ionisation energy

  • Ionisation energy increases
  • The number of protons increases
  • Same shielding /Atomic radius decreases
  • Same energy levels
  • Stronger attraction between nucleus and outer electron
  • Requires more energy to remove an electron
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8
Q

Deviations across the period (Group 3)

A

-Ionisation Energy decreases in each period at group 3 because u change from an S to a P sub level
- The electron is removed from a higher energy P sub level
- Weaker attraction between nucleus and outer electrons

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9
Q

Deviations across the period (group 6)

A
  • Ionisation energy decreases within each period at group 6 because the electrons pair up in a P orbital
  • There is a pair of electrons in a p-orbital
  • Extra repulsion means less energy is required to remove an electron
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10
Q

Successive Ionisation Energies

A

Successive IEs will always increase because:
- The positive charge on the ion increases
- The ionic radius decreases
- Nuclear attraction on the outer electron increases
- Its more difficult to remove an electron from a more positive ion
e.g C+

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11
Q

Jumps in ionisation energies

A

Large jump = an electron is removed from a principal energy level that is much closer to the nucleus
e.g if the jump is between the 3rd and 4th IE then there must’ve been 3 outer electrons so the element is in group 3

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12
Q

Metallic Bonding Defintion

A

Strong electrostatic forces of attraction between positive ions and delocalised electrons

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13
Q

Metals

A
  • Metal : A lattice of positively charged metal ions attracted to a sea of delocalised electrons
    -Metals can’t transfer electrons because there’s no non metal present.
  • So, the atoms merge their outer shells and there electrons become shared
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14
Q

Delocalised Electrons

A
  • Electrons have no fixed position
  • Positive ions will repel but the sea of electrons is attracted to the positive ions and will make the lattice very strong
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15
Q

What factors affect the strength of a metallic bond?

A
  • Higher ionic charge = stronger metallic bonds
  • More delocalised electrons = stronger metallic bonds
  • Smaller atomic radius = stronger metallic bonds

These make the positive ions more attracted to the delocalised sea of electrons

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16
Q

Properties of Metals

A
  • Good conductors of electricity and heat as the delocalised electrons are free to move and flow.
  • Have very high melting and boiling points as they have a a strong electrostatic attraction between the positive ions and delocalised electrons
  • Malleable and ductile
    Because there are layers of ions that can slide over each other
17
Q

Giant Covalent Structures
In period 2 & 3
Diamond

A

Diamond (carbon)
Each carbon bonded to 4 other carbon atoms
Strong covalent binds - require lots of energy to break
Conduct electricity? No because there are no delocalised electrons
High melting/boiling point because strong covalent bonds

18
Q

Giant Covalent Structures
Graphite (carbon)

A

Each carbon atom bonded to 3 other carbon atoms
- Forms a hexagonal layer
- Strong covalent bonds
Weak London forces between the layers
Conduct electricity? Yes. delocalised electrons are free to move and flow

19
Q

Giant Covalent Structures
Graphene (carbon)

A
  • 1 layer of graphite
  • Each carbon atom bonded to 3 other carbon atom
  • Forms a hexagonal layer
  • Strong covalent bonds
  • Conduct electricity? Yes delocalised electrons are free to move and flow
20
Q

Giant Covalent Structures
Silicon

A

Each silicon atom is bonded to 4 other silicon atoms
Seeing covalent bonds
Conduct electricity?
No, no delocalised electrons

21
Q

Bonding of period 2 elements

A

S block - Li & Be - Metallic bonding
P block - C,N,O,F - Covalent bonds
Neon - Monoatomic - Single atom

22
Q

Structure of period 2 elements

A

Li and Be - Giant metallic lattice
Carbon - Giant Covalent lattice
N2, O2, F2, Neon - Simple molecular

23
Q

Simple Molecular

A

Strong covalent bonds within the molecule
Weak IMFs between the molecules
All non-polar molecules
So weak London forces between the molecules that require less energy to break

24
Q

Bonding of period 3 elements

A

Bonds increase as you go across
Na, Mg, Al - Metallic bonding
Si, P, S, Cl - Covalent bonds
Ar - Monoatomic , Single atom

25
Structure of period 3 elements
Na, Mg, Al - Giant metallic lattice Si (silicon) - Giant covalent lattice P, S , Cl , Ar - Simple molecular P4, S8, Cl2, Ar
26
Melting point
Melting - **Some** of the attractive forces between the particles are broken They now move freely around ravished but still close together The **stronger** the forces, the more difficult it is to melt
27
Boiling point
**All** the attractive forces between the particles are broken They are free to move randomly
28
Melting/Boiling point of Period 2&3 Metals
Giant metallic lattices P2 - Li & Be P3 - Na, Mg, Al High MP/BP due to strong electrostatic attraction between positive ions and delocalised electrons
29
Melting/Boiling point of Period 2&3 elements Giant covalent
P2 - C P3 - Si **Very high** MP & BP due to **strong covalent bonds** which require lots of energy to break
30
Melting/Boiling point of Period 2&3 elements Simple Molecular
P2 - N2, O2, F2, Neon P3 - S8, P4, Cl2, Ar Low MP & BP because **weak London forces between molecules** that require less energy to break