Module 2: Electrons and Bonding (Chapter 5) Flashcards

1
Q

How do electrons orbit the nucleus?

A

In energy levels

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2
Q

In the first 4 energy levels (shells) how many electrons are in each?

A
1 = 2 
2 = 8
3 = 18
4 = 32
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3
Q

What is a shell?

A

A set of orbitals with the same quantum number (within the same energy level).

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4
Q

Define an atomic orbital

A

A region within an atom that can hold up to 2 electrons with opposite spin.

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5
Q

What are the 4 types of sub-shell?

A

s-, p-, d-, f-

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6
Q

How many orbitals in each sub-shell?

A

n=1 has 1 orbital
n=2 has 4 orbitals
n=3 has 9 orbitals
n=4 has 16 orbitals

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7
Q

Describe the s-orbital

A

Electron cloud is spherical
Can hold max of 2 electrons
Each energy level (shell) has 1 s-orbital
Greater the shell number, the larger the radius of the s-orbital

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8
Q

Describe the p-orbital

A

Shaped like a dumb-bell
Found from n=2 upwards
Each shell contains 3 p-orbitals (3x2e-)
Arranged at right angles to each other in Px, Py and Pz

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9
Q

Describe the d-orbital

A

Each shell from n=3 upwards contains 5 d-orbitals (10e-)

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10
Q

Describe the f-orbitals

A

From n=4 upwards.

Each shell contains 7 f-orbitals (14e-)

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11
Q

How are electrons represented in a box?

A

Half-headed arrows. Always fill in singularly first.

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12
Q

How can shorthand electronic configuration be written?

A

Use of noble gases in square brackets with remaining outer electron sub-shells.

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13
Q

What is an ion?

A

Electrically charged particle formed from the lose or gain of electrons.

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14
Q

What happens to configuration when a positive ion forms?

A

Electrons are removed from the highest energy orbitals (further from the nucleus).

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15
Q

What happens to configuration when a negative ion forms?

A

Electrons are added to the highest energy orbitals.

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16
Q

What is different about d-block elements when forming ions?

A

The 4s-sub-shell is filled before the 3d-sub-shell. This means the reverse is true when making ions. The 4s-sub-shell electrons are lost before the 3d-sub-shell electrons.

17
Q

Why are the noble gases so unreactive?

A

The s and p sub-shells are full. All the electrons are paired to another electron of opposite charge. They fulfil the Octet rule.

18
Q

What are other atoms trying to acheive?

A

Obtain the Octet rule. A noble gas electron configuration, by bonding with other elements - sharing or transferring electrons in chemical bonds.

19
Q

Define ionic bonding

A

Electrostatic attraction between a metal and non-metal, formed from the transfer of electrons, to form a giant ionic lattice structure.

20
Q

Why do ionic compounds have a high mpt and bpt?

A

Strong electrostatic forces of attraction between oppositely charged ions, requiring a lot of energy to overcome. Hence high mpt and bpt.

21
Q

Are ionic compounds soluble?

A

Soluble in polar solvents like water. Break down the lattice and surround each ion in solution. Partial charge of water causes the anion to be attracted to hydrogen and cation to oxygen. Compounds with larger charges will not be able to be broken down by water, as attraction is too strong.

22
Q

Do ionic compounds conduct electricity?

A

In a solid state no, but when molten or aqueous, the ions in the solution are mobile, so are mobile charge carriers. When solid the ions are fixed in position, and are not mobile charge carriers.

23
Q

What structure do ionic bonds form?

A

Giant ionic lattice

24
Q

What are the general rules for different groups, when forming ionic compounds?

A

Groups 1-3 lose electron to form cations
Group 4 don’t form ions as too much energy is required
Groups 5-7 gain electrons to form anions
Group 0 do not form ions as they are Nobel gases

25
Q

Define covalent bonding

A

Electrostatic attraction between a shared pair of electrons and the nuclei of the bonded atoms. There is overlap of the atomic orbitals, where the electrons are shared.

26
Q

What is the type of attraction in a covalent bond?

A

Attraction is localised between the nuclei of the two bonding atoms. This an result in a molecule forming.

27
Q

What are lone pair?

A

Electrons in the outer shell not used in bonding.
A concentrated region of negative charge around the atom.
Can influence the shape and chemistry of the molecules.

28
Q

Why are there exceptions to the Octet rule?

A

The Octet rule is not always possible to achieve.
May not be enough electrons to react an octet.
More than 4 pairs of electrons can form in the bonding.
Boron is an example of where only 3 pair of electrons can form due to only having 3 outer electrons.

29
Q

Why are elements in groups 5-7 of period 3 exceptions to the Octet rule?

A

The n=3 shell can hold 18 electrons. The is me and that more electron are available for bonding, so expansion of the Octet occurs.

30
Q

What are the general rules for the exceptions to the Octet?

A

Non-metals in group 5 can form 3-5 covalent bonds.
Non-metals in group 6 can form 2, 4 or 6 covalent bonds.
Non-metals in group 7 can form 1, 3, 5 or 7 cb.

31
Q

What happens in a double bond?

A

The electrostatic attraction is between 2 shared pair of electrons and the nuclei of the bonding atoms. E.g CO2

32
Q

What is a triple covalent bond?

A

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

33
Q

What is a dative bond?

A

Known as a coordinate bond, this is when a shared pair of electrons has been provided by one of the bonding atoms only.

34
Q

What are some of the proportions of simple covalent molecules?

A

Weak intermolecular forces between molecules - low energy to separate the molecules - low melting and boiling points.
Do not conduct electricity - no charged particles available.
Non-soluble in polar solvents, but soluble in polar solvents. E.g. hexane. This is due to London forces between the solvent and the molecule.

35
Q

Describe some of the properties of giant covalent structures

A

Joined by strong covalent bonds, meaning high melting and boiling points.
Not soluble in either polar or non-polar solvents. The covalent bonds are too strong to the broken.
Strength of covalent bonds are measured by ‘average bond enthalpy’.
Form a giant lattice structure.
Graphite is the only one which can conduct, due to the mobile delocalised electron.
Silicon dioxide is an example, where their is a tetrahedral structure, and is joined to 4 oxygen atoms.