Week 2 - Solutions; Mixtures; Media

Question 1

Define an atom

Answer 1

The smallest unit of matter with element - specific chemical properties

Question 2

Define nucleon

Answer 2

Proton or neutron

Question 3

Define an element

Answer 3

• A substance whose atoms all have the same number of
  protons
• Cant be broken down by chemical reactions

Question 4

Define isotope

Answer 4

Same number of protons but different number of neutrons

Question 5

Define ions

Answer 5

Atoms that contain different numbers of protons and electrons ( + or - charged )

Question 6

Define molecule

Answer 6

A substance formed when two or more atoms are chemically
bonded together

Question 7

Breifly explain the periodic table of elements

Answer 7

• Russian chemist Dmitri Ivanovich Mendeleev some 150 years ago
• Who based on this table not only corrected knowledge on some of the known elements, but was able
  to predict the existence and properties of other elements unknown at that time

Question 8

Define mixtures

Answer 8

Mixtures are combinations of two or more substances that are not
chemically combined

eg. Ocean water and beach sand are examples of mixtures

Question 9

Define compounds

Answer 9

Compounds are molecules that are made up of two or more different
elements

e.g. H2O, CO2, NaCl, silica sand

Question 10

Explain homogenous mixtures

Answer 10

• Solutions are homogenous liquid mixtures, in which the solute (minor
  component) is dissolved in the solvent (major liquid component)
• Distribution of the different substances is even (e.g. salt in water).

Question 11

Explain heterogenous solutions

Answer 11

Solution where the different substances are distributed unevenly (e.g. sand in water)

Question 12

Define growth liquid

Answer 12

• Liquid, semi-solid or solid mixtures designed to support the growth of a cell population. They contain diverse nutrients that are necessary for cell growth

Question 13

What is liquid growth media referred to as

Answer 13

Liquid growth media are usually referred to as broths

Question 14

Explain solid liquid growth media

Answer 14

Solid growth media are usually prepared by adding agar or agarose to the liquid media

Question 15

Explain agar fully

Answer 15

• Agar is a substance that is derived from red algae. It is a white powder
  when dry, and turns to jelly when mixed with water
• The jellifying agent of agar is the agarose, a polysaccharide that forms a
  network of fibers as shown in the electron microscope image

Question 16

Define atomic mass ( ma )

Answer 16

Mass of an atom expressed in unified atomic mass units

Question 17

Define unified atomic mass unit ( u )

Answer 17

Half mass of one carbon 12 atom

Question 18

Define average atomic mass of an element

Answer 18

Some of the masses of its isotopes each multiplied by its natural abundance

Question 19

Define atomic weight ( Ar )

Answer 19

Ratio of the average atomic mass of an element to 1u ( 0.5 atomic mass 12C )

Question 20

Define molecular weight ( Mr )

Answer 20

Some of the atomic weights of all atoms of the molecule

Question 21

Define formula weight ( FW )

Answer 21

Molecular weight for substances that do not consist of individual molecules

Question 22

Define molar mass ( M )

Answer 22

• The mass of one mole of a substance in gram
• It is equal to the atomic or molecular weight of the substance

Question 23

State Avogadro law

Answer 23

At the same temperature and pressure equal volumes of gases have equal number of particles