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SQA Higher Chemistry Unit 1 > Unit 1(b) - Periodicity > Flashcards

Unit 1(b) - Periodicity Flashcards

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1
Q

What is a periodic pattern?

A

A pattern which repeats across a period in the periodic table

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2
Q

What did Mendeleev use to arrange the then known elements?

A

Increasing masses and similar chemical properties

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3
Q

How is the modern periodic table arranged?

A

Increasing atomic number

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4
Q

In the modern periodic table, what are trends related to?

A

Bonding and structure

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5
Q

What is the covalent radius of an atom?

A

Half the distance between the nuclei of two bonded atoms of the element

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6
Q

What happens to atomic size as you move across a period?

A

Atomic size decreases, as the increasing nuclear charge pulls electrons closer to the nucleus

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7
Q

What happens to atomic size as you move down a group?

A

Atomic size increases as an extra electron shell is added, as well as nuclear attraction decreasing due to shielding by inner electrons

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8
Q

What is the density of a substance?

A

It’s mass per unit volume

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9
Q

What happens to density as you move across a period?

A

The general trend is that in any period, density first increases from group 1 to a maximum in the centre, then decreases again towards group 0

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10
Q

What happens to density as you move down a group?

A

Density increases as the mass of the atom is increasing faster than the volume

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11
Q

What do melting and boiling points indicate?

A

The strength of the forces between particles

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12
Q

What happens to mps and bps as you move across a period?

A

Increase from group 1 to group 4 (group 4 elements are covalent networks), then decrease to group 0

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13
Q

What happens to mps and bps as you move down group 1?

A

Melting and boiling points decrease as there is a decrease in attraction between atoms

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14
Q

What happens to mps and bps as you move down group 7

A

Melting and boiling points increase as LDF attractions between molecules increase

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15
Q

What is the first ionisation energy?

A

The energy required to remove one mole of electrons from one mole of gaseous atoms

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16
Q

What are the second (and subsequent) ionisation energies?

A

The energies required to remove further moles of electrons

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17
Q

What happens to ionisation energy as you move across a period?

A

Ionisation energies increase as the increasing nuclear charge pulls electrons closer to the nucleus

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18
Q

What happens to ionisation energy as you move down a group?

A

Ionisation energy decreases as the outer electrons are further from the nucleus, and the shielding effect from the inner electrons reduces the nuclear attraction for outer electrons

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19
Q

What is electronegativity?

A

A measure of the attraction an atom in a bond has for the electrons of the bond

20
Q

Which element is the most electronegative?

A

Fluorine

21
Q

What happens to electronegativity as you move across a period?

A

Electronegativity increases as the nuclear charge increases, attracting the electrons more strongly to the nucleus

22
Q

What happens to electronegativity as you move down a group?

A

Electronegativity decreases because the number of electron shells increases. This means electrons are further from the nucleus and the shielding effect of inner electrons increases

23
Q

What are the properties and structure of elements related to?

A

The types of bonding present

24
Q

What is a metallic bond?

A

Electrostatic attraction between positive nuclei and delocalised outer electrons

25
Q

What do metallic structures consist of?

A

A giant lattice

26
Q

What is metallic bond strength?

A

A measure of the no. of outer electrons. The greater the no. of electrons, the stronger the metallic bond

27
Q

What are some characteristics of metals?

A
  • Shiny
  • Malleable
  • Ductile
  • Good electrical and heat conductors
28
Q

What happens to metallic character as you move across a period?

A

It decreases as the mobility of the electrons as they are restricted by the increasing nuclear charge

29
Q

What happens to metallic character as you move down a group?

A

It increases as outer electrons are held more loosely due to shielding

30
Q

What is the relationship between metallic bond strength and metallic character?

A

The stronger the metallic bond, the less the metallic character

31
Q

How does the size of metal atoms relate to melting and boiling points?

A

Smaller metallic atoms have larger melting and boiling points

32
Q

What are metal boiling points dependant on?

A
  • How many electrons are in the outer shell

* No. of electron shells

33
Q

Why are the noble gases stable?

A

They have full outer electron shells, meaning they are chemically stable and monatomic

34
Q

Why do noble gases form liquids and solids at low temperatures, despite being monatomic?

A

Weak intermolecular forces - LDF

35
Q

What is LDF?

A

The attraction between the temporary dipoles caused by uneven distribution of moving electrons

36
Q

What is a dipole

A

An unequal distribution of charge

37
Q

What is a covalent bond?

A

The electrostatic attraction between the positive nuclei and the negative shared electrons

38
Q

What kinds of bonding are present in diatomic molecules?

A

Strong intramolecular bonding (covalent) and weak intermolecular bonding (LDF)

39
Q

Give examples of discrete covalent molecular solids

A

Phosphorous (P4), sulphur (S8), and carbon (fullerenes)

40
Q

Why are phosphorous and sulphur solids at room temperature, whereas chlorine is a gas?

A

P and S are larger with more atoms, so have more opportunities for LDF. Chlorine forms diatomic molecules which are gaseous at room temperature

41
Q

What is a covalent network?

A

A covalent network structure consists of a giant lattice of covalent lay bonded atoms

42
Q

What is the structure of boron?

A

Boron forms B12 groups which are inter bonded with each other, resulting in an element almost as hard as diamond. It has a very high melting point

43
Q

What two network forms does carbon exist as?

A

Graphite and diamond

44
Q

What are some properties of graphite?

A
  • Layers of atoms in hexagonal plates
  • 3/4 outer electrons covalently bonded, 4th outer electron moves within layer
  • Conducts electricity due to delocalised electron
  • Soft, slippery, used as a lubricant
45
Q

What are some properties of diamond?

A
  • Regular tetrahedral structure
  • All 4 outer electrons covalently bonded
  • Does not conduct electricity
  • Hardest natural substance, used in cutting tools
46
Q

What element is similar in structure to carbon?

A

Silicon

SQA Higher Chemistry Unit 1 (3 decks)

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