chemical bonding

Question 1

what is a bond?

Answer 1

a bond is any attractive force between particle

Question 2

what is ionic bonds?

Answer 2

ionic bond is the transfer of electrons between metallic an non-metallic elements. the metal atom donates electrons and the non-metals accept electrons. ions are formed

Question 3

what happened once ions are formed?

Answer 3

they are held together by strong electrostatic forces of attraction (ionic bond)

Question 4

ionic bond must be formed between non-metals and non-metals, true or false?

Answer 4

false, between metals and non-metals

Question 5

give the physical properties of ionic compounds.

Answer 5

1. relatively high mp and bp
2. do not conduct electricity in solid state but conducting in the molten (liquid) state or in aqueous state
3. have a regular crystal shape
4. they are brittle and shatter easily on impact

Question 6

why an ion is a charged particle?

Answer 6

an ion is a charged particle because it contains an unequal number of protons and electrons

Question 7

what is covalent bonding?

Answer 7

covalent bonds are formed between non-metals and other non-metals

Question 8

what is involved in covalent bonding?

Answer 8

only the valence electron

Question 9

give the physical properties of covalent bond.

Answer 9

1. simple molecular substances have low mp and bp.
2. they do not conduct electricity when in the solid or liquid state. this is because they consist of molecules which are neutral and not ions
3. they are usually insoluble in water but soluble in organic solvent
4. in solid state, simple molecular substance exist as molecular crystal

Question 10

describe the structure of metal.

Answer 10

in metals, the metal lattice consists of positive ions surrounded by a sea of mobile electrons. they are free to move about between the positive ions

Question 11

what is meant by metallic bond?

Answer 11

attractive force between positively charged ions and negatively charged mobile electrons

Question 12

give reason why metal is a good conductor of heat and electricity in solid and molten states?

Answer 12

presence of mobile electrons surrounding the lattice of ;ositive metals ions

Question 13

give reason why metal have high density?

Answer 13

close packing of metal ions

Question 14

give reason why metal are hard, high mp and bp

Answer 14

strong attractive forces between the lattice of metal ions and the sea of electrons

Question 15

give reason why metal are malleable ( can be beaten into sheets) and ductile ( can be drawn out into long, thin wires)

Answer 15

due to orderly packing of metal atoms. they can easily slide over one another

Question 16

give reason why metals can form alloys with other elements

Answer 16

atoms of other elements can enters the holes in the lattice

Question 17

why covalent bond have low mp and bp?

Answer 17

due to weak forces of attraction between the molecules

Question 18

why covalent bond does not conduct electricity?

Answer 18

because molecules are not charged particles

Question 19

why ionic bond conduct electricity in molten state?

Answer 19

because the positive and negative ions can move around

Question 20

what is element?

Answer 20

an element cannot be broken down into simpler substances by chemical or electrical method

Question 21

what is a compound?

Answer 21

a compound is formed when 2 or more atoms chemically combined together and can be broken down into simpler substance by chemical methods such as heating or using electricity

Question 22

what is a mixture?

Answer 22

a mixture is formed when 2 or more substance are not chemically combined together. it can be separated by physical methods

Question 23

difference between compounds and mixtures?

Answer 23

compound made up of molecules of one kind such as water, meanwhile mixture made up of molecules of more than one kind such as seawater contain NaCl & H2) molecules

compound has fixed composition by mass, meanwhile mixture has no fixed composition

compound components can be separated by chemical methods, meanwhile mixture components can be separated by physical means

Question 24

give examples of giant metallic lattice

Answer 24

zinc and iron

Question 25

give examples of giant molecular lattice

Answer 25

SiO2, diamond, graphite, polyethene

Question 26

give examples of simple molecular substance

Answer 26

iodine, CH4

Question 27

give examples of giant ionic lattice

Answer 27

NaCl and MgO

Question 28

why methane is gaseous at rtp?

Answer 28

it has very weak intermolecular forces of attraction l

Question 29

physical properties of iodine

Answer 29

iodine is a dark purple crystalline solid with a purple vapour

Question 30

physical properties of simple molecular substance

Answer 30

1. usually are liquids or gases at room temperature. this is due to weak intermolecular forces of attraction between the molecules.
2. low mp and bp (usually below 200). only the weak intermolecular forces between the molecules are overcome when water boils
3. do not conduct electricity as they do not contain ion or electrons that are free to move
4. insoluble in water but soluble in organic solvent

Question 31

describe giant covalent structure

Answer 31

a large network of atoms is held together by strong covalent bonds

Question 32

difference between diamond and graphite structure?

Answer 32

in graphite, carbon atoms are arranged in layers of hexagonal rings. while in diamond, the carbon atoms are arranged tetrahedrally and bonded by covalent bonds. All of the electrons in diamond are used for bonding, while only 3 electrons in each carbon atom of graphite are used in bonding.

due to a network of strong covalent bond, large amount of heat is required to melt the structure

Question 33

structure of graphite

Answer 33

graphite is a soft,grey solid, made of flat layers of carbon atoms.
each carbon atom covalently bondedwith 3 other carbon atoms. they are arranged in hexagonal rings of 6 atoms. the forces between the layers of carbon atoms are weal so they can easily slide past each other

used in pencil lead and as a lubricant