Atoms and Molecules

Question 1

define what it is meant by the key term ‘atom’

Answer 1

atoms are units of matter that form all chemical substances. each type of atom (eg - oxygen, nitrogen) is known as a ‘chemical element’

Question 2

state the 4 components of atoms

Answer 2

1. atoms are made of protons, neutrons and electrons
2. protons and neutrons are found in the atomic nucleus
3. electrons are found orbiting the atomic nucleus in orbitals
4. an atom is most stable when the outer orbital has a pair of electrons

Question 3

what percentage of atoms in the body are made from Hydrogen, Oxygen, Carbon and Nitrogen

Answer 3

1. Hydrogen - 63%
2. Oxygen - 26%
3. Carbon - 9%
4. Nitrogen 1%

Question 4

what percentage of atoms in the body is made up from mineral elements

Answer 4

0.7% total atoms in the body

Question 5

what percentage of atoms in the body is made up from trace elements

Answer 5

less than 0.01% total atoms in the body

Question 6

define what it is meant by the key term ‘atomic number’

Answer 6

the atomic number is the total number of protons that an atom has

Question 7

state 2 facts about the atomic number

Answer 7

1. different atoms have different amounts of protons so the atomic number helps us distinguish between elements
2. as atoms are electrically neutral, the atomic number also tells us how many electrons the atom has

Question 8

define what it is meant by the key term ‘atomic mass’

Answer 8

atomic mass indicates an atoms mass in relation to other atoms based upon carbon having an atomic mass of 12

Question 9

define what it is meant by the key term ‘Dalton’

Answer 9

a Dalton (d) is the unit used to measure atomic mass. one dalton is equal to 1/12 the mass of a carbon atom

Question 10

define what it is meant by the key term ‘isotope’

Answer 10

an isotope is a different version of the same atom where the total number of neutrons in the atom has changed

Question 11

state 2 facts about isotopes and radiation

Answer 11

1. isotopes are unstable so can randomly release energy or even components of the isotope itself
2. this is known as radiation and such isotopes are known as ‘radioisotopes’

Question 12

state 2 benefits of radioisotopes

Answer 12

1. the special qualities of radioisotopes are of great practical use in medicine (eg - killing cancer cells)
2. radioisotopes can also be useful is medical diagnosis

Question 13

state what it is meant by the key term ‘gram atomic mass’

Answer 13

1. the gram atomic mass of a chemical element is the amount of the element, in grams, equal to the numerical value of it’s atomic mass
2. eg - 12g of carbon (assuming it’s all C12) is 1g atomic mass of carbon

Question 14

define what it is meant by the key term ‘ion’

Answer 14

1. an ion is an atom which has gained, or lost, one or more electron(s)
2. the result is a full orbital in the atoms valence shell meaning it has become chemically stable

Question 15

define what anions and cations are

Answer 15

1. anions are ions created where atoms have gained electrons and has become negatively charged
2. cations are ions created where atoms have lose electrons and has become positively charged

Question 16

state 3 facts about ions

Answer 16

1. because of their charge, ions can conduct energy when dissolved in water
2. the ionic forms of mineral elements are often referred to as electrolytes
3. electrolytes are used to carry electrical charges across cell membranes so serve as an electrical current in certain cells

Question 17

state 4 facts about the anatomic composition of the body

Answer 17

1. H, O, C and N account for 99% of the atoms in the body
2. the 7 essential mineral elements are the most abundant substances dissolved in the ejxtracelleur and intracelleur fluids
3. most of body’s calcium and phosphorus make the solid matrix of bone tissue
4. the 13 essential trace elements are required for normal body growth and function

Question 18

state what it is meant by the key term ‘molecules’

Answer 18

molecules are formed when two or more atoms bond together

Question 19

define what it is meant by the key term ‘compound’

Answer 19

a compound is where two or more molecules bond together

Question 20

state what it is meant by a ‘covalent bond’

Answer 20

a covalent bond is where two or more atoms with partially filled valance shells bind together by sharing electrons to fill their valance shells

Question 21

state 3 facts about covalent bonds

Answer 21

1. covalent bonds make atoms chemically stable
2. covalent bonds are the strongest chemical bond between atoms
3. covalent bonds can usually only be broken via heat or enzyme action

Question 22

define the key term ‘electronegativity’

Answer 22

electronegativity is the measure of an atoms ability to attract electrons in a covalent bond

Question 23

what factors effect electronegativity

Answer 23

1. the more positively charged an atoms atomic nucleus is the greater the atoms electronegativity
2. electronegativity decreases the greater the distance between the atoms valance shell and atomic nucleus increases

Question 24

define what it is meant by the key term ‘polar-covalent bonds’

Answer 24

polar covalent bonds occur when two, or more, atoms bond and the electrons will spend more time orbiting the atom with a greater electronegativity creating a polarity across the covalent bond

Question 25

state 3 facts about polar molecules

Answer 25

1. polar bonds do not have a net electrical charge as the overall charge of the molecule is stable 2. polar molecules tend to be more soluble in water than non-polar molecules 3. polar molecules readily dissolve in blood, interstitial fluid and intracelleur fluid

Question 26

define what it is meant by the key term 'non-polar covalent bonds'

Answer 26

non-polar covalent bonds is where a covalent bond is formed between two, or more, atoms of the same electronegativity

Question 27

what are non-polar molecules

Answer 27

non polar molecules are molecules that contain a large proportion of non-polar covalent bonds

Question 28

state 2 facts about non-polar molecules

Answer 28

1. electrons are, or nearly, evenly shared between atoms in the covalent bond so no unequal charge is formed 2. when in fluid, they usually associate with polar molecules as a 'carrier' to prevent the non-polar molecules from coming out of the solution

Question 29

state what it is meant by the key term 'ionic bond'

Answer 29

an ionic bond is formed via chemical attraction between opposingly charged atoms

Question 30

define what it is meant by the key term 'hydrogen bond' (H-bond)

Answer 30

1. H-bonds are formed when two polar molecules in close proximity of each other form an electrical attraction between them 2. such bonds may also form on an intra-anatomical Lebel

Question 31

state 3 facts about H-bonds

Answer 31

1. represented by dashed lines in diagrams 2. although weak individually, when in large numbers, they play a key role in deterring the shape of large molecules 3. essential in physiology as shape effects function (eg - enzymes)

Question 32

define what it is meant by the key term 'ionization'

Answer 32

ionisation is the process of forming ions. this process can happen either, on atoms individually, or atoms covalently linked in a molecule

Question 33

what are the two groups of atoms that usually undergo ionisation

Answer 33

1. the Carboxyl group (COOH) - ionises when the O2 linked to H captures the H's electron releasing a proton 2. the amine group (NH2) - binds to the H+ released by the carboxyl group

Question 34

define what it is meant by the key term 'free radicals'

Answer 34

free radicals are atoms with an unpaired electron in an orbital of their valance shell

Question 35

state 3 facts about free radicles

Answer 35

1. atoms are most stable with paired electrons outer orbital 2. free radicles are unstable and can react with other atoms in the process of oxidation

Question 36

how can free radicles be treated in the body

Answer 36

antioxidants, such as vitamins A and C, can donate electrons to these free radicles and inactivatete them

Question 37

how are free radicles produced

Answer 37

free radicles can be produced via exposure to radiation or via toxin ingestion

Question 38

state how free radicles can be used in immunology

Answer 38

1. free radicles are formed by the actions of certain enzymes in some cells (eg - WBC's) 2. free radicles remove electrons from outer shells of atoms in the cell wall/cell membrane of pathogens to become stable, in turn breaking down pathogens

Question 39

define what it is meant by the key term 'solute'

Answer 39

a solute is something that can be dissolved in a liquid

Question 40

define what it is meant by the key term 'solvent'

Answer 40

a solvent is a liquid at which solutes can be dissolved in

Question 41

define what it is meant by the key term 'solution'

Answer 41

a solution is the product of solutes being dissolved into a solvent

Question 42

define what it is meant by the key term 'acids'

Answer 42

acids are molecules which release hydrogen ions/protons

Question 43

define what it is meant by the key term 'a base'

Answer 43

1. a base is any substance which is able to accept hydrogen ions/protons 2. consequently, bases decrease the proton concentration in water

Question 44

1. define what it meant by the key term 'strong acid'

Answer 44

a strong acid is an acid which completely, or nearly completely, becomes fully ionised in solution

Question 45

define what it is meant by the key term 'acidity'

Answer 45

acidity refers to the concentration of free/unpaired protons/hydrogen ions in a solution

Question 46

define what it is meant by the key term 'pH'

Answer 46

1. pH is the negative logarithm to the base 10 of the hydrogen ion/proton concentration 2. pH = -log(H+) 3. for example, 10-7 mol/l = pH7

Question 47

what is the usual homeostatic pH range

Answer 47

7.35-7.45 pH

Question 48

define what it is meant by the key term 'concentration'

Answer 48

concentration is the amount of a solute present within a unit volume of solution

Question 49

how is concentration expressed when the chemical structure of a molecule is known

Answer 49

when the chemical structure of a molecule is known, concentration is expressed based upon the number of solute molecules in solution, using the measurement of mass called the 'molecular weight'

Question 50

define what it is meant by the key term 'molecular weight'

Answer 50

1. molecular weight is the sum of all the atomic masses of all the atoms within that molecule 2. eg - glucose molecular weight = 180

Question 51

what is the value of 'Avogadro's number'

Answer 51

6 x 10^23

Question 52

what does 'Avogadro's number' state

Answer 52

1. Avogadro's number states that 1 mole of any molecule will contain the same number of molecules as any other molecule 2. therefore, 1 mol/l glucose will contain the same number of molecules as 1 mol/l any other molecule