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Chemistry > Chemical Bonding > Flashcards

Chemical Bonding Flashcards

1
Q

What is a coumpound

A

A substance that is made up of two or more different elements combined together chemically

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2
Q

What is the octet rule

A

When bonding occours, atoms tend to reach an electron arrangement with eight electrons in the outermost shell

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3
Q

What are expections to the Octet rule

A

Transition elements dont obey the octet rule and often have more or less than 8 electrons in the outer shell
Elements near helium tens to have 2 electrons in the outer shell

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4
Q

What is an ion

A

A charged atom/ group of atoms

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5
Q

What is a postive ion called

A

Cations

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6
Q

What is a negative ion called

A

Anions

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7
Q

What is an ionic bond

A

The force of attraction between oppositly charged ions in a compound

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8
Q

What do you use to show the formation of ionic bonding

A

Bohr diagrams, dot and cross diagrams

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9
Q

What structure do ionic compounds have

A

Crystal lattice structure

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10
Q

What are crustal lattice structures dertimined by?

A

X-ray crystallography

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11
Q

Charateristics of ionic compounds

A

Hardness- hard substances due to strong ionic bonds and crystal lattice structures.
Melting and boiling points- high melting and boiling points due to strong ionic bonds and crystal lattice structure.
Conduction of electricity.Dont condict electricity in solid state but do conduct electricity in the molten state or when dissolved in water as the ions are free to carry the charge.

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12
Q

What are elements placed in the transition metal block but not transition elements, and why are they an expection?

A

Sc and Zn are not transition metals.Sc and Zinc have different properties to the other transition elements

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13
Q

what is a transition metal

A

An elements that forms at least one ion with a partially filled d sublevel.

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14
Q

What are the properties of transition elements

A

Transition elements have varaible valency. Sc only forms SC3+ ions and zn only forms Zn 2+ ions
transition elements usually form colourful compounds, scandium and zinc only form white compounds.
Transition elements are widely used as catalysts. Sc and zn show little catalytic activity.

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15
Q

varable valency

A

the number of atoms of different elements in which a certain element can combine with.

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16
Q

What is a covalent bond

A

One which involves that sharing of electrons between atoms.

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17
Q

What is a molecule

A

Agroup of atoms joined together. Its the smallest partical of an element or compound that can exist independently

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18
Q

What can molecules only be used for

A

Covalent compounds

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19
Q

What is the Valency of a element

A

The number of atoms of hydrogen or any other monovalent element with which each atom of the element combines

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20
Q

What is a single bond

A

one pair of electrons are shared between two atoms

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21
Q

What is a double bond

A

two pairs of electrons are shared between two atoms

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22
Q

What is a triple bond

A

three shared pairs of electrons

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23
Q

what is a group of organic compounds called

A

Aldehydes

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24
Q

What is a sigma bond

A

A sigma bond is fored due the head-on overlap of two orbitals

(All single covalent bonds can be describes as a sigma bond)

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25
Q

What is formed when two atomic orbitals overlap

A

Molecular orbital

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26
Q

What is a pi bonf

A

A pi bond is formed due to sideways/ lateral overlap of P orbitals

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27
Q

Are Sigma bonds stronger or Pi bonds stronger

A

There is less overlap between orbitals in a pi bond, therefore it is weaker than a sigma bond

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28
Q

What does a single covalent bond consist of

A

1 sigma bond

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29
Q

What does a double covalent bond consist of

A

1 sigma and 1 pi bond

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30
Q

What does a triple covalent bond consist of

A

1 sigma and two pi

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31
Q

Charateristics of ionic and covalent compounds

Their differences

A

Ionic
Contains a network of ions in the crystal
usually hard and brittle
high melting and boiling points
usually solid at room temperture
conduct electricty when dissolved in water or molten

Covalent
contain individual molecules
usually soft
usually have low melting and boiling points
usually liquid or gasses at room temperature
dont conduct electricity ( no ions present)

32
Q

What is VSEPR

A

Valance shell electron pair repulsion theory states the shape of a molecule depends on the number of pairs of electrons in the valence shell of the central atom

33
Q

Why do electrons repel eachother

A

electrons are negativily charged, the electron pairs repel eachother and arrange themselves in space to be as far apart as possible.

34
Q

what are loan pairs

A

Both electrons come from the same atom

35
Q

What are bond pairs

A

each electron comes from a different atom

36
Q

What is a dative corrdinate bond

A

Special type of covalent bond where one atom supplies both the electrons
Eg. NH4+

37
Q

A molecule has 4 electron pairs,4 bond pairs,0 loan pairs what shape it it?

A

Tetrahedral

38
Q

A molecule has 3 electron pairs,3 bond pairs,0 loan pairs what shape it it?

A

Trigonal planer

39
Q

A molecule has 2 electron pairs,2 bond pairs,0 loan pairs what shape it it?

A

Linear

40
Q

A molecule has 4 electron pairs,3 bond pairs,1 loan pairs what shape it it?

A

Pyramidial

41
Q

A molecule has 4 electron pairs,2 bond pairs,2 loan pairs what shape it it?

A

V-shaped / bend

42
Q

What is the bond angle of a tetrahedral

A

109.5

43
Q

What is the bond angle of a trigonal planer

A

120

44
Q

What is the bond angle of a linear

A

180

45
Q

What is the bond angle of a pymidial

A

107

46
Q

What is the bond angle of a v-shaped

A

104.5

47
Q

Which molecule shapes are not symmetrical

A

Pyramidial and v-shaped

48
Q

What is electronegativity

A

The relative force of attractions two atoms in a molecule have for a shared pair of electrons in a covalent bond

49
Q

What can electronegivity be used to predict

A

Polarity of covalent bonds
perdict which compounds are ionic and which ones are covalent

50
Q

In a covalent between two of the same atoms, how are the electrons shared

A

the pair of electrons are shared equally between the two atos in the molecule

51
Q

Im a covalent bond bwetween two different atoms, how are the electrons shared

A

more attracted to one atom than another.

52
Q

What is a charge indicated by?

A

Delta δ

53
Q

What does the word polar mean

A

the bonding electrons aren’t shared equally. There is a partial postive and partial negative charge on the molecule.
These partial charges are seperated by some distance,

54
Q

What is the term pure covalent bond

A

refers to a covalent bond where there is equal sharing of electrons

55
Q

What does a moleule need to have in order to be a polar molecule

A

It cant be symmetrical

56
Q

Why is water clearly a polar molecule

A

Water is v shaped, cant be symmetrical.
warer is a good solvent. most ionic substances and most polar covalent substances dissolve in water. Opposite charges are attracted towards eachother.

57
Q

What does a EN difference of >1.7 indicate?

A

Ionic bonding

58
Q

What does a EN difference of 0.4 -1.7 indicate?

A

Polar Covalent bond

59
Q

What does a EN difference of < (or equal) 0.4 indicate?

A

Non polar covalent bond

60
Q

What is the demostrating polarity used to show

A

to show if a compund (usually a liquid)is polar.Water is polar. ( has tempoary postive charges associated) water will deflect when a postively or negativily charged rod comes near. The H postive will be attracted towards the negativily charged rod.Similarly, the O (negative) will be sttracted to th negativitly charged rod.
Cyclohexane is an organic compound that is non-polar (no deflection

61
Q

What is Intramolecular bonding and give examples

A

boing that takes place within a molecule
Ionic, Polar covalent, non polar covalent

62
Q

What in Intermolecular bonding and give example

A

Forces of attraction between molecules
van der waals forces, dipole-dipole forces, Hydrogen bonding

63
Q

What are Van der waals forces

A

weak attractive forces between molecules resulting from the formation of tempoary dipoles

64
Q

Where do Van der Waals forces exist between

A

All non-polar molecules, Nobel gas atoms

65
Q

Properties of van der waals forces

A

Have low boiling points (often gasses at room temperture) Insoluble in water( they are non polar and dont form hydrogen bonds with water)
Very weak attractive force

66
Q

As the atom size increases, Van de waals forces increase in strenght, why?

A

the number of electrons present increases (bigger atomic number)
Number of tempoary dipoles formed increases.
The strenght of van der waals forces increases.
bigger the molecule/atom, higher the boiling point

67
Q

What are dipole dipole forces

A

Forces of attraction netween the negative pole of one molecule an the postive pole of another

68
Q

diople diople forces exist between…

A

all polar molecules

69
Q

which polar molecules do dipole dipole forces not exist betweeen

A

H2O,HF,NH3

70
Q

Properties of dipole-dipole forces

A

Dipole dipole forces are stonger than van der waals forces.
substances with dipole dipole forced between their molecules have highter melting and boiling points.

71
Q

What is hydrogen bonding

A

Hydrogen bonds are particular types of dipole dipole attractions between moleules in which hydrogen atoms are bonded to nitogen, oxygen or fluorine

72
Q

How does hydrogen bonding work

A

The hydeogen acts as a bridge between two electronegative atoms in seperate molecules. Flurinr, oxygen and nitrogen are very small electronegative elements. gives the molecules strong polarity

73
Q

Properties of hydrogen bonding

A

Strongest intermolecule force.
higher boiling points and melting point.
Gives increased solubility in water.

74
Q

H2O has a higher boiling point than HF and NH3, why?

A

H2O has twice as many haygrogen bonds between its molecules (HF)
Greater electronegivity value, greater
dipole (more polar)(NH3)

75
Q

Hydrogen bonding in everyday life

A

Ensures water is liquid at room temp so life can exist on earth.
Synthetic clothing- bullet proof vests/protective clothing.
hydrogen bonds in wool help it absorb water. hydrogen bonds in water give it a high surface tension.

76
Q

What does the hydrogen bonding in water allow it to do?

A

gives water a unusually high boiling point (ensures water is liquid at room temp)
Gives water a high water tension.
(water to flow against gravity in plants)
Ensures ice is less dense than water
(fish can survive in lakes in the winter)

Chemistry (14 decks)

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