5- Electrons and Bonding Flashcards

1
Q

What are shells regarded as?

A

Energy levels

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2
Q

What happens to the energy as the shell number increases?

A

Energy increases

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3
Q

What is the shell number or energy level number referred to as?

A

Principal quantum number

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4
Q

How many electrons are in the 1st shell?

A

2

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5
Q

How many electrons are in the 2nd shell?

A

8

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6
Q

How many electrons are in the 3rd shell?

A

18

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7
Q

How many electrons are in the 4th shell?

A

32

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8
Q

What are shells made up of?

A

Atomic orbitals

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9
Q

How many electrons can be held in an orbital?

A

one or two, NO MORE

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10
Q

Define orbital

A

the region around the nucleus which can hold 2 electrons with opposite spins

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11
Q

What are the different orbitals?

A

S-orbitals
P-orbitals
D-orbitals
F-orbitals

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12
Q

How many orbitals does each type contain?

A

S-orbitals - 1
P-orbitals - 3
D-orbitals - 5
F-orbitals - 7

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13
Q

How many electrons can be held in each orbital type?

A

S-orbitals - 2
P-orbitals - 6
D-orbitals - 10
F-orbitals - 14

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14
Q

What is the shape of an s-orbital?

A

Spherical

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15
Q

What is the shape of a p-orbital?

A

dumbbell

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16
Q

What are the rules for orbital fillings?

A

-orbitals fill in order of increasing energy
-orbitals with the same energy are occupied singly first then pair up with opposite spins

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17
Q

Where does this rule cause confusion for 3d and 4s?

A

-the 3d sub-shell has a higher energy than the 4s
-so the 4s fills before the 3d
-then when the 4s fills up it takes higher energy then the 3d, so the 4s looses electrons first

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18
Q

Explain the rule of electrons pair with opposite spins

A

-electrons are negatively charged so repel one another
-electrons have a property called spin which is either up or down
-two electrons in an orbital pair up with opposite spins to help counteract the repulsion between the negative charges of 2 electrons

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19
Q

Explain the rule of orbitals with the same energy which occupy singly first

A

-within a sub-shell, the orbitals have the same energy
-one electron occupies each orbital before pairing begins
-this prevents any repulsion between paired electrons until there is no further orbital available at the same energy level

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20
Q

How can electron configuration be shortened?

A

-expressed in more simple terms of the previous noble gas in the periodic table plus the outer electron sub-shells
1s2 can be represented as [He]
1s2 2s2 2p6 - [Ne]
1s2 2s2 2p6 3s2 3p6 - [Ar]

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21
Q

What is the shorthand notation of Lithium?

A

[He]2s1

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22
Q

What is the shorthand notation of Na?

A

[Ne]3s1

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23
Q

What is the shorthand notation of K?

A

[Ar]4s1

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24
Q

What happens in terms of energy sub-shells when forming ions?

A

The highest energy sub-shells loose or gain electrons

25
Q

What are cations?

A

Positive ions formed when atoms loose electrons

26
Q

What are anions?

A

Negative ions formed when atoms gain electrons

27
Q

What is ionic bonding?

A

The electrostatic attraction between the positive and negative ions

28
Q

What are common cations?

A
  • metal ions (eg. Na+ , Ca2+ , Al 3+)
    -ammonium ions ( NH4+)
29
Q

What are common anions?

A

non metal ions (Cl- O2-)
polyatomic ions (NO3- SO4 2-)

30
Q

What is the result of ions attracting oppositely charged ions in all directions?

A

Giant ionic lattice

31
Q

How are the melting and boiling points of ionic compounds explained?

A

-high temperatures are required to provide the energy sufficient to overcome the strong electrostatic attraction between the ions
-most ionic compounds have high melting and boiling points
-almost all ionic compounds are solids at room temperature

32
Q

What happens to the melting points for giant ionic lattices, when ionic charge increases?

A

-melting point increases as there is a stronger attraction between ions

33
Q

Are ionic compounds soluble?

A

-some ionic compounds are soluble and they dissolve in polar solves (eg. water)
-the ones that do not:
have a high charge density (eg. Al 3+), and the ionic attraction is too strong for the polar solvents to break down the lattice structure, and to surround each ion in solution. so these compounds will not be very soluble

34
Q

What does solubility require?

A

-the ionic lattice must be broken down
-polar solvent (eg. water molecule) must attract and surround the ions

35
Q

What does the solubility of ionic compounds depend on?

A

-the relative strengths of the attractions within the giant ionic lattice and the attractions between ions and water molecules

36
Q

When can ionic compounds conduct electricity?

A

-not in solid state
-once molten or dissolved in water

37
Q

Why can’t ionic compounds conduct electricity when solid?

A

-the ions are in a fixed position
-there are no mobile charge carries

38
Q

Why can ionic compounds conduct electricity when molten or dissolved in water?

A

-the solid ionic lattice breaks down
-the ions are now free to move as mobile charge carries

39
Q

Summarise the properties of most ionic compounds

A

-high melting and boiling points
-tend to dissolve in polar solvents such as water
-conduct electricity only in the liquid state or in aqueous solution

40
Q

What is the ionic lattice structure of sodium chloride?

A
  • Each Na+ ion is surrounded by 6 Cl- ions
    -Each Cl- ion is surrounded by 6 Na+ ions
    -Each ion is surrounded by oppositely charged ions strongly attracted in all directions, forming a giant ionic lattice
41
Q

What is the electron configuration of Krypton?

A

1s2,2s2,2p6,3s2,3p6,4s2,3d10,4p6

42
Q

What is covalent bonding?

A

the strong electrostatic attraction between a shared pair of electrons and the nuclei of bonded atoms

43
Q

When atoms does covalent bonding occur between?

A

-non-metallic elements (H2, O2)
-compounds of non-metallic elements (eg. H20 , CO2)
-polyatomic ions (NH4+)

44
Q

What is covalent bonding in terms of atomic orbitals?

A

The overlap of atomic orbitals, each containing one electron, to give a shared pair of electrons

45
Q

How does covalent bonding differ to ionic bonding?

A

-For covalent bonding the attraction is localised: attraction acting only on the shared pair of electrons and the nuclei of the bonding atoms
-Ionic, however; attracts in all directions in 3 dimensions

46
Q

How can covalent bonding be displayed?

A

With dot and cross diagrams

47
Q

What is a double bond?

A

The electrostatic attraction is between 2 shared pairs of electrons, and the nuclei of the bonding atoms

48
Q

What is a triple bond?

A

The electrostatic attraction is between 3 shared pairs of electrons, and the nuclei of the bonding atoms

49
Q

What is a dative covalent bond?

A

The shared pair of electrons has been supplied by one of the bonding atoms only (originally a lone pair)

50
Q

Give an example of a dative covalent bond?

A

-ammonia molecule
-it donates its lone pair of electrons to a H+ ion
-forming an ammonium ion

51
Q

What is average bond enthalpy?

A

-a measurement of covalent bond strength
-the larger the value the stronger the bond

52
Q

What is the shell formula?

A

2n^2

53
Q

At what stage do atoms not follow the octet rule?

A
  • from n=3, when a d-subshell becomes available for the expansion
    -this is called the expansion of the octet
54
Q

How many bonds does Carbon form?

A

4

55
Q

How many bonds does Nitrogen form?

A

3

56
Q

How many bonds does Oxygen form?

A

2

57
Q

How many bonds does Hydrogen form?

A

1

58
Q

What happens to electrons is covalent and ionic bonding?

A

ionic - electrons transferred
covalent - electrons shared