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Chemistry > Bonding And Structure > Flashcards

Bonding And Structure Flashcards

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1
Q

Is strontium more reactive than calcium and why?

A

Yes, IE is less/it loses electrons more easily

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2
Q

Observations when Ca is added to water (3 marks)

What is the product formed?

A
  1. Ca sinks and rises
  2. White ppt
  3. Colourless gas bubbles

Products: calcium hydroxide and hydrogen

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3
Q

Why can’t sodium chloride be prepared directly using Na and HCl?
What is the alternative method?

A

Na’s too reactive

HCl+NaOH

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4
Q

How do giant metallic, graphite, and giant ionic conduct electricity? At what state? Why?

A
  1. Solid state/aq and molten for ionic
  2. Delocalised electrons move to form current (GM and graphite)
    Mobile ions allows electricity to flow

Why?
Delocalised electrons / mobile ions are present in that state

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5
Q

Electrical conductivity of graphite. Explain. (3 marks)

A 
In graphite each carbon atom is bonded to three other carbon atoms (1) (using covalent bonding)
The other (outer) electron for each carbon atom is delocalised (1), 
throughout the structure and is able to move (1), conducting electricity
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6
Q

Similarity between CsCl and NaCl lattices.

A

Both are cubic

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7
Q

How to draw H-bond with water molecules? (3 marks)

A
  1. At least two water molecules (or one water with another molecule) are shown
  2. Partial charges labelled
  3. H-bond labelled
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8
Q

Why can ice float on water? 3 marks

A

ice is less dense / molecules are further apart (1)
ice is a hydrogen bonded lattice (1)
(partially) broken down in water (1)

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9
Q

Explain the increasing trend of electronegativity across the period. (3 marks)

A

Increase in number of protons / charge on the nucleus (1)
But same number of electron shells / no increase in shielding (1)
Greater power to attract (bonding pair of) electrons (1)

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10
Q

Describe the structure of graphite. (4 marks)

A

Hexagonal layers of carbon atoms
Each carbon bonded to three others
Weak Van der Waals forces between layers
Delocalised electrons above and below plane

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11
Q

Describe the structures of graphite, giant ionic and giant metallic. (Each 2 marks)

A

Graphite: Giant covalent structure OR Hexagonal layers of carbon atoms
: Delocalized electrons between the layers

Aluminium: Lattice of positive metal ions with (sea of) delocalized electrons

Caesium chloride: (Lattice of) anions and cations / giant ionic

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12
Q

During fractional distillation, explain why hydrocarbons containing few carbon atoms distil at lower temperatures than hydrocarbons with many carbon atoms. [3] What is the definition of that?

A

Long chain hydrocarbons have more/stronger intermolecular forces (1)
Van der Waals forces specified (1)
Higher temperatures/more energy required to break these forces (1)

Def: separation of longer chain and shorter chain hydrocarbons by boiling point difference.

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13
Q

Why does IE increase down group 7?

A

molecular size increases down group (1)

Greater van der Waals

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14
Q

Why is sth soluble in water? (2 marks)

A

Cannot form hydrogen bond 1) with water molecules 1)

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15
Q

What is ionic bond? Why does it have high boiling point? (2 marks)

A

Electrostatic forces between the oppositely charged ions (1)

ionic bonds are / ionic lattice is very strong so large amount of energy needed (1)

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16
Q

Why does diamond have a higher boiling point than iodine gas? (3 marks)

A

Van der Waals forces between molecules need to be broken to form iodine gas (1)
Covalent bonds need to be broken to form a gas from diamond/graphite (1)
Van der Waals forces are much weaker than covalent bonds (1)

17
Q

What is giant metallic bond? (2 marks)

A

Regular array of metal ions surrounded by a ‘sea’ of delocalised valence electrons (1)
Strong attraction between the positive ions and the delocalised electrons (1)

18
Q

Why are metallic compounds malleable and able to conduct electricity? (2marks)

A

Malleable because when a force is applied the layer of metal ions slide over each other forming a new shape (1)
Conduct electricity since under a potential difference the delocalised electrons flow / the delocalised electrons flow towards the positive potential

19
Q

Why does HCl have higher boiling point than SiH4? (2 marks)

A

Cl more electronegative than Si

therefore intermolecular forces are stronger

20
Q

Define hydrogen bonding. (3 marks)

A

Intermolecular bond formed when hydrogen attached to a highly electronegative atom (NOF) (1)
is bonded to an electronegative atom in another molecule (1)
forming very strong dipole – dipole attraction (1)

21
Q

Explain pH scale to a member of the public? (4 marks)

A

The pH scale runs from 0-14 / measure of acidity / alkalinity + concentration of hydrogen ions(1)
pH <7 acid / >7 alkali (1)
More H+ ions, lower pH (1)
acid stronger as pH value decreases / alkali stronger as pH value increases (1)

22
Q

Why is the bond covalent?

A

All the bonding electrons are shared equally between the atoms

23
Q

How to answer structure and bonding questions in general? (3 marks)

A
  1. Bond name
  2. Describe the bond (ionic: lattice of oppositely charged ions
    metallic: regular array of metal ions surrounded by sea of delocalised electrons)
  3. If bp: less electrons+smaller molecular size->weak IMF-less energy to require to break
    If electricity: mobile ions/free electrons present to allow flow of current/carry electricity
24
Q

Explain why Cl2 is gas but I2 is a solid in room temperature. (3 marks)

A
  1. VDW stronger in I2 than Cl2
  2. I2 has more electrons than Cl2
  3. More energy is required to overcome the force
25
Q

Why does NaCl have a higher boiling point than NaI? ( 2 marks)

A
  • iodide ion larger than chloride ion so less attraction to sodium ion
  • less difference in electronegativity so NaI not as ionic as NaCl
26
Q

Do ClF2- and ClF2+ have the same shape? Why? (3 marks)

A

No
- : 2 bond pairs and 3 lone pairs
+: 2 bond pairs and 2 lone pairs

different numbers of electron pairs will give rise to different shapes (1)

27
Q

What determines chem properties of an atom

A

Electronssssssss

Chemistry (14 decks)

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