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Chemistry > 5) Electrons and bonding > Flashcards

5) Electrons and bonding Flashcards

1
Q

Energy increases as shell number _?

A

increases

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2
Q

Define principal quantum number n

A

a number representing the relative overall energy of each orbital, which increases with distance from the nucleus

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3
Q

What are the sets of orbitals with the same n-value referred to as?

A

electron shells or energy levels

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4
Q

Define atomic orbital

A

a region around the nucleus that can hold up to 2 e-, with opposite spins

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5
Q

Describe a s-orbital

A

spherical shape

as n increases, radius increases

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6
Q

Describe a p-orbital

A

dumb-bell shape

as n increases, reaches further away from the nucleus

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7
Q

Define sub-shell

A

a group of orbitals of the same type within a shell

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8
Q

Describe the filling of orbitals

A

orbitals fill in order of increasing energy
electrons pair with opposite spins
orbitals with the same energy are occupied singly first (bus-seating rule)

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9
Q

What is special about the 3d sub-shell?

A

it is at a higher energy level than the 4s sub-shell so it is filled after and emptied after the 4s sub-shell

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10
Q

What does electron pairing with opposite spins help to do?

A

counteract the repulsion between the negative charges of the 2 electrons

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11
Q

When orbitals with the same energy are occupied singly first (bus-seating rule), what does it prevent?

A

any repulsion between paired electrons until there is no further orbital available at the same energy level

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12
Q

Define electron configuration

A

a shorthand representation that shows how electrons occupy sub-shells in an atom

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13
Q

In an electron configuration, how are shells listed?

A

in shell order rather than in order of filing

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14
Q

How can electron configurations be expressed more simply?

A

in terms of previous noble gas plus outer electron sub shells

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15
Q

When are positive ions / cations formed?

A

when atoms lose electrons

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16
Q

When are negative ions / anions formed?

A

when atoms gain electrons

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17
Q

Define ionic bonding

A

the electrostatic attraction between positive and negative ions

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18
Q

In ionic bonding electrons are _ whereas, in covalent bonding electrons are _?

A

transferred

shared

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19
Q

Define giant ionic lattice

A

3D structure of oppositely charged ions, bonded together by strong ionic bonds

20
Q

Give 3 features of giant ionic lattices

A

high melting and boiling points
many dissolve in polar solvents e.g. water
conducts electricity as a liquid or aqueous solution

21
Q

Why do ionic lattices containing ions with greater ionic charges have higher melting points?

A

there is stronger attraction between ions

22
Q

What two conditions must be met for a giant ionic lattice to dissolve in a polar solvent?

A

the ionic lattice is broken down

solvent molecules e.g. water attract and surround the ions in solution

23
Q

How are giant ionic lattices able to conduct electricity as a liquid or aqueous solution?

A

the ions are free to move as mobile charge carriers

24
Q

Define covalent bonding

A

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

25
Q

Where can covalent bonding occur?

A

between atoms in non-metallic elements
compounds of non-metallic elements
polyatomic ions

26
Q

Define covalent bond

A

the overlap of atomic orbitals, each containing 1 electron to give a shared pair of electrons

27
Q

Give 3 common features of a covalent bond

A
  • the shared pair of electrons is attracted to the nuclei of both of the bonding atoms
  • the bonded atoms often have outer shells with the same electron structure as the nearest noble gas
  • the attraction is localised, acting solely between the shared pair of electrons and the nuclei of the two bonded atoms (forming a molecule)
28
Q

Define molecule

A

the smallest part of a covalent compound that can exist while retaining its chemical identity, consisted of two or more atoms covalently bonded together

29
Q

Define displayed formula

A

a formula showing the relative positioning of all the atoms in a molecule and the bonds between them

30
Q

Define lone pair

A

an outer shell pair of electrons that is not involved in chemical bonding

31
Q

How many covalent bonds can carbon form?

A

4

32
Q

How many covalent bonds can nitrogen form?

A

3

33
Q

How many covalent bonds can oxygen form?

A

2

34
Q

How many covalent bonds can hydrogen form?

A

1

35
Q

What is special about Boron?

A

has only 3 outer shell electrons which can be paired - showing predictions for bonding cannot be based solely on noble gas electron structure

36
Q

For elements in period 2, the n=2 outer shell can hold just 8 electrons. But what is special about phosphorous, sulfur and chlorine?

A

the n=3 outer shell can hold 18 electrons, so more electrons are available for bonding

37
Q

Give the formula for different fluorides containing phosphorous

A

PF3

PF5

38
Q

Give the formula for different fluorides containing sulfur

A

SF2
SF4
SF6

39
Q

Give the formula for different fluorides containing chlorine

A

ClF
ClF3
ClF5
ClF7

40
Q

What is significant about SF6

A

expansion of the octet where sulfur’s outer shell contains more electrons than the nearest noble gas
only possible from the n=3 shell when a d-sub-shell becomes available for expansion

41
Q

In a double covalent bond, the electrostatic attraction is between _ and the nuclei of the bonding atoms

A

two shared pairs of electrons

42
Q

In a triple covalent bond, the electrostatic attraction is between _ and the nuclei of the bonding atoms

A

three shared pairs of electrons

43
Q

Define dative covalent / coordinate bond

A

a shared pair of electrons in which the bonded pair has been provided by one of the bonding atoms only

44
Q

In a dative covalent bond, what would the shared electron pair have been originally?

A

a lone pair of electrons on one of the bonded atoms

45
Q

What does average bond enthalpy serve as a measurement of?

A

covalent bond strength

46
Q

The larger the value of average bond enthalpy, the _ the covalent bond.

A

stronger

Chemistry (31 decks)

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