Principles of Chemistry DS

Question 1

what is the equation for calculating relative atomic mass?

Answer 1

(mass of isotope x % abundance) + (mass of isotope x % abundance) DIVIDED BY 2

Question 2

what is the charge on an ion of silver?

Answer 2

Ag+

Question 3

what is the charge on an ion of zinc?

Answer 3

Zn2+

Question 4

what is the charge on an ion of hydrogen?

Answer 4

H+

Question 5

what is the charge on an ion of hydroxide?

Answer 5

OH-

Question 6

what is the charge on an ion of ammonium?

Answer 6

NH4 +

Question 7

what is the charge on an ion of carbonate?

Answer 7

CO3 2-

Question 8

what is the charge on an ion of nitrate?

Answer 8

NO3 -

Question 9

what is the charge on an ion of sulphate?

Answer 9

SO4 2-

Question 10

define covalent bond

Answer 10

form when 2 non metals react - the atoms share electrons to gain a full outer shell and produce a molecule.

Question 11

define molecule

Answer 11

form when 2 or more atoms chemically bond together.

Question 12

explain the melting/boiling points in terms of the structure of ionic compounds

Answer 12

very high.
this is because of the strong electrostatic attraction between oppositely charged ions.
lots of energy is needed to break them.

Question 13

can ionic compounds conduct electricity when solid? give a reason

Answer 13

no
because ions can’t move freely so can’t carry charge.

Question 14

can ionic compounds conduct electricity when molten (liquid)? give a reason

Answer 14

yes because ions can move freely and therefore can carry charge.

Question 15

can ionic compounds conduct electricity in a solution? (dissolved in water) give a reason

Answer 15

yes because ions can move freely and therefore can carry charge.

Question 16

what is the structure of an ionic compound and how is the lattice held together?

Answer 16

• ions in an ionic compound arranged in a regular pattern (a lattice structure).
• there are strong electrostatic attractions between the oppositely charged ions.
• these are the ionic bonds.

Question 17

define mass number

Answer 17

total number of protons and neutrons in an atom.

Question 18

define atomic number

Answer 18

number of protons in an atom.

Question 19

define relative atomic mass

Answer 19

the average mass of all the isotopes of an element.

Question 20

define isotope

Answer 20

atoms of the same element that have the same number of protons but a different number of neutrons.

Question 21

name 3 physical properties of a metal

Answer 21

malleable
shiny
high density.

Question 22

name 3 physical properties of a non metal

Answer 22

dull
brittle
low density.

Question 23

name 3 chemical properties of a metal

Answer 23

high melting point
good conductor of heat
good conductor of electricity.

Question 24

name 3 chemical properties of a non metal

Answer 24

low melting point
poor conductor of heat
poor conductor of electricity.

Question 25

elements in each group have the same number of.... and the group tells us....

Answer 25

how many outer shell electrons.

Question 26

elements in each period have the same number of.... and the period tells us....

Answer 26

number of electron shells.

Question 27

can simple covalent molecules conduct electricity? why/why not?

Answer 27

no because they don't have free electrons or ions to carry charge.

Question 28

define allotrope and give an example

Answer 28

different forms of the same element e.g. diamond, graphite, and fullerenes are different forms of carbon.

Question 29

define giant covalent bonding

Answer 29

contain many atoms, each joined to adjacent atoms by covalent bonds in a giant regular lattice.

Question 30

why do giant covalent structures (e.g. diamond and graphite) have high melting points?

Answer 30

they have lots of strong covalent bonds that need a lot of energy to break.

Question 31

why can graphite conduct heat and electricity?

Answer 31

each carbon atom has one delocalised electron which can carry charge.

Question 32

why can diamond not conduct heat or electricity?

Answer 32

there are no free electrons or charged particles to move and carry charge.

Question 33

explain the melting/boiling points of covalent molecules

Answer 33

- have high melting/boiling points - because the bonds are very strong due to strong intermolecular forces of attraction between a pair of electrons and the 2 nuclei of the atoms.

Question 34

describe the structure of buckminsterfullerene (C60)

Question 35

how does the structure of buckminsterfullerene relate to its properties?