Week 2

Question 1

What information can you get from a periodic table

Answer 1

1. Atomic Mass. ie. 10 (Ne = Neon) which tells you that there are 10 protons and therefore must have 10 electrons
2. Mass Number which is the sum of the proton and neutrons, and which is 20.18 for Neon as given in the periodic table. We know that there are 10 protons and by dividing the number of protons from the Mass (20.18 - 10 = 10) we then know that the number of neutrons for Neon is 10.

Question 2

Describe what you understand under Electrons

Answer 2

• Electrons are arranged in shells/energy levels/clouds/orbits
• The first shell has up to 2 electrons
• The second shell has up to 8 electrons
• The third shell holds between 8-18 electrons
• The valence shell is the outermost shell of an atom

Question 3

(NB) What do you understand under valence sell?

Answer 3

The valence shell is the outermost shell of an atom (outer ring of the number of electrons)
Valence shells fill up as follows:
• 1st shell – two electrons
• 2nd shell – 8 electrons
• 3rd shell – 8 electrons minimum

Question 4

Chemistry hierarchy

Answer 4

• MATTER – “stuff” (see, smell, touch etc)
• ELEMENTS – makes up matter and is composed of atoms
• ATOMS – makes up elements and is composed of protons,
neutrons and electrons

Question 5

Definition of Molecule:

Answer 5

Molecule: ANY two or more atoms held together by chemical bonds
• Ie molecule of an element = two identical atoms (H + H = H2) or (O + O = O2)
• Ie molecule of a compound = two or more different atoms (Na + Cl = NaCl)

Question 6

Definition of Compound

Answer 6

• Compound: Two or more different kinds of atoms chemically bonded
together (Eg H + Cl = HCl)

Question 7

How do atoms form these molecules and

compounds?

Answer 7

• A chemical bonds result from electrons of two atoms interacting
• When a valence shell of an atom is not completely full ( then it is unstable) it will often
look to share electrons with others

Question 8

Types of chemical bonds

Answer 8

• When two atoms share electrons – covalent bond
• If an atom donates an electron to another atom – ionic bond
Atom which donates the electron becomes positively charged —- Cation (+)
Atom which accepts the electron becomes negatively charge —– Anion (-)

Question 9

(NB) what is cellular respiration?

Answer 9

Glucose + Oxygen become Carbon dioxide + water + ATP

Question 10

what do Inorganic compounds mean?

Answer 10

• Don’t contain carbon and carbon-hydrogen bonds
- Acids, bases, water and salts
• Water is the most abundant inorganic compound in our bodies
- 60-80% of the volume of living cells
• Why do we have so much water? Why is it useful?
- High heat capacity
- High heat of vaporisation
- Polar solvent properties
- Important reactant
- Cushioning
• Salts
- Salts are ionic compounds
- Contain cations other than H+, and anions other than OH-
- When dissolved in water dissociate into their ions
_ Water simply overcomes the attraction between
the ions
- Eg NaCl, CaCO3, KCl
- All ions are “electrolytes” as they can conduct
electrical charge in solution
_ Important for nerve impulse transmission

Question 11

Name the Properties of Acids

Answer 11

• Acids and bases are also electrolytes
- Ionise and conduct electricity in solution
• Properties of Acids
- Sour taste
- Dissolves (reacts) with many metals
- Can cause burns
- Releases hydrogen ions when dissolved in water

Question 12

Name the properties of Bases

Answer 12

Properties of bases
• Bitter taste
• Feel slippery
• Bases are referred to as “proton acceptors”
- Can “take up” or “accept” hydrogen ions (H+) in acceptable amounts
- Common bases include the hydroxides (OH-)
NaOH → Na+ + OH-
- The resulting hydroxyl ion then “accepts” a proton present in the solution
OH- + H+ → H2O- The end result is water and the removal of a proton from the solution

Bases reduce the acidity of solution making them more alkaline

Question 13

pH scale allows us to measure the concentration of hydrogen ions in solution

Answer 13

• pH stands for “power of hydrogen”
• Measures the relative concentration of H+ ions in a solution
• Ranges from 0-14
• pH of 1 is highly acidic, pH of 7 is neutral, pH 14 strongly basic/alkaline
• pH scale is logarithmic
- Every variation of a single pH unit represents a 10-fold difference in H+
concentration
• A pH of 1 means a 10-fold greater number of H+ ions than a pH of 2

Question 14

What do you understand under - pH: Acid-base concentration

Answer 14

1 ACIDS
• More hydrogen ions (H+) in solution the more acidic the solution
• The more acidic a solution, the lower the pH
HCl → H+ + Cl
2 BASES
• The higher the concentration of base (ie hydroxyl ions (OH-))
• The more H+ ions are taken out of the solution (ie the lower the conc. of H+)
• The less acidic a solution is, therefore the higher the pH
NaOH → Na+ + OH-
OH- + H+ → H2O

Question 15

What is an ION

Answer 15

1. an Ion is an atom, or a group[ of atoms that have an elactrical chage
2. A Positine ION is calld a Cation
3. a Negative ion is called an anion
4. Polytomic ions is an group of ions that have a charge.

Question 16

What do you understand under - Variations in the strength of acids and bases

Answer 16

1. Acid/base strength is determined by the amount of dissociation
   when placed in solution
   • Dissociation= the formation of ions from a molecule

• A strong acid like HCl dissociates completely when
placed in water

HCl → H+ + ClH

• A weak acid like H2CO3 only partially dissociates when placed in water

2CO3 ↔ H+ + HCO3-

Question 17

What are buffers?

Answer 17

It’s a Chemical Sytems that are design to resist chnages in then pH levels

Question 18

What is the most important bufer system in our body?

Answer 18

Carbonic acid-bicarbonate buffer

Question 19

What is the ph level of a basic and what do you understand under the term basic

Answer 19

Basic = alciline = > pH 7

Question 20

Acidosis?

Answer 20

• Blood is acidic

* pH is lower than the homeostatic range

Question 21

Alkalosis?

Answer 21

• Blood is too basic

* pH is higher than the homeostatic range

Question 22

What is the difference between organic and inorganic compound?

Answer 22

The primary difference between organic vs. inorganic compounds is that organic compounds always contain carbon while most inorganic compounds do not contain carbon. (NB - belangrik)

1. Examples of Organic Compounds or Molecules
   Molecules associated with living organisms are organic. These include nucleic acids, fats, sugars, proteins, enzymes, and hydrocarbon fuels. All organic molecules contain carbon, nearly all contain hydrogen, and many also contain oxygen.

DNA
table sugar or sucrose, C12H22O11
benzene, C6H6
methane, CH4
ethanol or grain alcohol, C2H6O

2. Examples of Inorganic Compounds
   Inorganics include salts, metals, substances made from single elements and any other compounds that don’t contain carbon bonded to hydrogen. Some inorganic molecules do, in fact, contain carbon.

table salt or sodium chloride, NaCl
carbon dioxide, CO2
diamond (pure carbon)
silver
sulfur

Question 23

What are organic compounds?

Answer 23

1. Molecules containing carbon that have carbon-hydrogen bonds
2. Molecules unique to living systems all contain carbon and hence are considered organic compounds (—NB—)
3. Four main types in the human body: (—NB—)
   • Carbohydrates
   • Lipids
   • Proteins
   • Nucleic Acids

Question 24

Explain what you understand of Carbohydrates

Answer 24

1. Represent 1-2% of cell mass
2. Contain carbon (C), hydrogen (H) and oxygen (O)
3. Building Blocks: Monosaccharides
4. Important energy source
5. Two types of carbohydrates
   a Simple: contain 1-2 sugar molecules
   • One sugar: monosaccharide, two sugars: a disaccharide
   b Complex: contain strings of sugar molecules
   • Multiple sugars: polysaccharide

Question 25

What is Monosaccharides and Disaccharides which is a simple carbohydrate.

Answer 25

``` Mono = one Di = two saccharides = Sugar ```

Question 26

What are polysaccharides?

Answer 26

It is a complex carbohydrate Poly = multiple saccharides = Sugar

Question 27

What are a Lipids

Answer 27

Lipids are our fats and oils 1. Lipids also contain carbon (C), hydrogen (H) and oxygen (O) • Overall less oxygen molecules than carbohydrates • Insoluble in water • Form approximately 12% of the human body (NB) 2. Examples include: (---NB---) • Neutral fats (triglycerides) • Phospholipids (find in our membranes) • Steroids 3. Neutral fats (triglycerides) • Fats and oils • Building blocks: fatty acids and glycerol • Stored energy source 4. Phospholipids • Modified triglycerides • Building blocks: fatty acids, glycerol, phosphorus • Cell membranes 5. Steroids • Building blocks: four hydrocarbon rings • Cholesterol

Question 28

What do you know about Proteins?

Answer 28

1. Compose 10-30% cell mass 2. All contain Carbon (C), Oxygen (O), Hydrogen (H) and Nitrogen (N) 3. Building blocks: Amino Acids (---NB---) • 20 different amino acids in nature • Contain a basic amine group (NH2), carboxyl group (COOH) and R-group • All amino acids have the same structure, only differing by their R-group 4. Proteins are long chains of amino acids • Form 3D structures

Question 29

What do you know about Enzymes?

Answer 29

1. Enzymes are one type of protein a. Act as catalysts to accelerate biochemical reactions, don’t cause reactions (---NB---) b. Specific to a single, or small group of similar reactions (---NB---) • Aren’t used up in the process → stay the same c. Act like a lock and key d. Enzymes are often named for the type of reaction they catalyse • Hydrolases – add water during hydrolysis • Oxidase – adds oxygen • -‘ase’ usually indicate enzymes (NB)

Question 30

What do you know about Nucleic acids?

Answer 30

1. Contain Carbon (C), Oxygen (O), Hydrogen (H), Nitrogen (N), Phosphorus (P) 2. Most commons nucleic acids are DNA and RNA (---NB---) a. Deoxyribo(se) nucleic acid (DNA) and ribo(se) nucleic acid (RNA) 3. Building blocks of nucleic acids: nucleotides 4. Five major varieties • Adenine (A), Thymine (T), Uracil (U) Cytosine (C) and Guanine (G) • A, G, C, T found in DNA • A, G, C, U found in RNA

Question 31

NB - Structure of DNA - 1. T and A always bind to each other 2. C and G always bind to each other

Answer 31

Important to know that 1. T and A always bind to each other 2. C and G always bind to each other

Question 32

How does RNA differ from DNA?

Answer 32

1. RNA is single-stranded 2. Base Uracil is substituted for Thymine 3. Deoxyribose is replaced with ribose

Question 33

What is simple vs complex carbohydrates (---NBN---)

Answer 33

Simple: contain 1-2 sugar molecules Complex: contain strings of sugar molecules

Question 34

How do Buffering Stabilises pH

Answer 34

A buffer is a chemical that, when present in a solution (e.g. blood), causes that solution to resist changes in its pH. Some proteins, especially albumin and haemoglobin, are good buffers. Another important buffer that is found in the human body is the bicarbonate - carbonic acid buffer system. This buffer system can be described by the following reaction. ↔ in the reaction below simply means the reaction is reversible and can go in either direction. H2CO3 (carbonic acid) ↔ H+ + HCO3- (bicarbonate ion)