Topic 2 (incomplete)

Question 1

ELEMENT

Answer 1

Consists of only 1 type of atom
- Unique physical & chemical properties
- Cannot be separated into a simpler
type of matter

Question 2

o MOLECULE

Answer 2

• A structure that consists of 2 or more
  atoms that are chemically bound
  together
• E.g. H2O, CO2, O2 , N2, H2
• Note: O2 , N2, and H2 always exist as
  diatomic molecules in nature

Question 3

o MOLECULE

Answer 3

• A structure that consists of 2 or more
  atoms that are chemically bound
  together
• E.g. H2O, CO2, O2 , N2, H2
• Note: O2 , N2, and H2 always exist as
  diatomic molecules in nature

Question 4

COMPOUND

Answer 4

A substance composed of 2 or more
different elements which are chemically
bound together
- Properties differ from that of constituent
elements
- Fixed composition (w.r.t. mass and
number of atoms of different elements)

Question 5

o MIXTURE

Answer 5

A group of 2 or more elements and/or
compounds (components) that are
physically combined
- Retain their original properties
- E.g. NaCl + H2O or benzene + toluene

Question 6

DIFFERENCE BETWEEN AN ELEMENT, A
MOLECULE AND A COMPOUND:

Answer 6

• An element consists of only 1 kind of atom
  (E.g. Ne, Fe, Hg, etc.)
• A molecule is a substance that consists of 2 or
  more atoms that are chemically bound
  together
  (E.g. H2O, CO2, O2 , N2, H2, etc.)
• A compound is a molecule composed of 2 or
  more different elements which are chemically
  bound together
  (E.g. H2O, NH3, CO2, etc.)

Question 7

Heterogeneous mixture

Answer 7

• Visible boundaries between components

Question 8

o Homogeneous mixture

Answer 8

• No visible boundaries because components are
  mixed as individual atoms, ions and molecules
• Also called a solution
• Solutions exist in all 3 phases

Question 9

The distinction between mixtures and compounds

Answer 9

Physically mixed → can be separated by physical
means; in this case by a magnet
- Chemically reacted → cannot be separated by physical

Question 10

Typical separation processes:

Answer 10

• Evaporation
• Distillation
• Filtration
• Precipitation
• Centrifugation etc

Question 11

Expressing component amounts in a compound or
mixture as:

Answer 11

• A percentage (sum of individual components adds up to 100%)
• A fraction (sum of fractions adds up to 1)

Question 12

LAW OF MASS CONSERVATION

Answer 12

Mass is conserved during a chemical reaction.
o Each molecule in a compound has its elements in the same proportions
by mass (e.g. CO2 has 1 parts C by mass + 2 parts O by mass).
o The total mass remains unchanged because the atoms of the reactants
are just rearranged into products.

Question 13

Principle of mass conservation:

Answer 13

Matter cannot be created nor destroyed.

o The total mass of substances does not change.
o MASS IN = MASS OUT

Question 14

Principle of mass conservation:

Answer 14

Matter cannot be created nor destroyed.

o The total mass of substances does not change.
o MASS IN = MASS OUT

Question 15

DALTON’S ATOMIC THEORY, What does it explain

Answer 15

the conservation of mass…

Question 16

DALTON’S ATOMIC THEORY

Answer 16

All matter consists of atoms
- Atoms of one element cannot be converted to
atoms of another element
- Atoms of an element have the same number of p+
and e-
, which determine the chemical properties of
an element
- Compounds form through chemical bonding of 2 or
more elements in specific proportions.
- Since every atom has a fixed mass, and during a
chemical reaction atoms are combined, there is no
mass change overall.

Question 17

Mass spectroscopy → determines

Answer 17

atomic mass
* Atomic mass is calculated as the average of the masses of its
commonly occurring isotopes weighted according to their natural
abundance. (therefore not integers on periodic table)
Atomic mass = SUM (isotopic mass) (fractional abundance)

Question 18

1 amu =

Answer 18

1/12 of the mass of a carbon -12 atom

Question 19

POLYATOMIC BONDING

Answer 19

o 2 or more covalently bonded
atoms with a resultant charge
(positive or negative)

Question 20

IONIC COMPOUNDS – WITH MONATOMIC IONS

Answer 20

Question 21

Transitional elements with monoantomic ions. What are the systematic names and the common names

Answer 21

Question 22

Transitional elements with monoantomic ions. What are the systematic names and the common names

Answer 22

Question 23

What does the ous or ic after the monotomic ions mean?

Answer 23

ous → lower charge
- ic → higher charge

Question 24

Polyatomic ions

Answer 24

Question 25

IONIC COMPOUNDS – ACIDS

Answer 25

2 TYPES of ACIDS:
- Binary acids
- Oxoacids

Question 26

o Binary acids are formed when certain

Answer 26

gaseous compounds
dissolve in water.
* Naming of binary acids:
prefix hydro- + anion nonmetal root + suffix –ic + the word
acid
* Common binary acids:
- HCl → hydrochloric acid

Question 27

o Naming of oxoacids similar to naming of oxoanions

Answer 27

• Except for 2 suffix changes:
• Anion –ate suffix becomes an –ic suffix in the acid
• Anion –ite suffix becomes an –ous suffix in the acid