Week 2 Flashcards
What information can you get from a periodic table
- Atomic Mass. ie. 10 (Ne = Neon) which tells you that there are 10 protons and therefore must have 10 electrons
- 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.
Describe what you understand under Electrons
- 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
(NB) What do you understand under valence sell?
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
Chemistry hierarchy
• 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
Definition of Molecule:
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)
Definition of Compound
• Compound: Two or more different kinds of atoms chemically bonded
together (Eg H + Cl = HCl)
How do atoms form these molecules and
compounds?
• 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
Types of chemical bonds
• 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 (-)
(NB) what is cellular respiration?
Glucose + Oxygen become Carbon dioxide + water + ATP
what do Inorganic compounds mean?
• 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
Name the Properties of Acids
• 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
Name the properties of Bases
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
pH scale allows us to measure the concentration of hydrogen ions in solution
• 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
What do you understand under - pH: Acid-base concentration
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
What is an ION
- an Ion is an atom, or a group[ of atoms that have an elactrical chage
- A Positine ION is calld a Cation
- a Negative ion is called an anion
- Polytomic ions is an group of ions that have a charge.
What do you understand under - Variations in the strength of acids and bases
- 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-
What are buffers?
It’s a Chemical Sytems that are design to resist chnages in then pH levels
What is the most important bufer system in our body?
Carbonic acid-bicarbonate buffer
What is the ph level of a basic and what do you understand under the term basic
Basic = alciline = > pH 7
Acidosis?
- Blood is acidic
* pH is lower than the homeostatic range
Alkalosis?
- Blood is too basic
* pH is higher than the homeostatic range
What is the difference between organic and inorganic compound?
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)
- 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
- 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
What are organic compounds?
- Molecules containing carbon that have carbon-hydrogen bonds
- Molecules unique to living systems all contain carbon and hence are considered organic compounds (—NB—)
- Four main types in the human body: (—NB—)
• Carbohydrates
• Lipids
• Proteins
• Nucleic Acids
Explain what you understand of Carbohydrates
- Represent 1-2% of cell mass
- Contain carbon (C), hydrogen (H) and oxygen (O)
- Building Blocks: Monosaccharides
- Important energy source
- 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
What is Monosaccharides and Disaccharides which is a simple carbohydrate.
Mono = one Di = two saccharides = Sugar
What are polysaccharides?
It is a complex carbohydrate
Poly = multiple
saccharides = Sugar
What are a Lipids
Lipids are our fats and oils
- 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) - Examples include: (—NB—)
• Neutral fats (triglycerides)
• Phospholipids (find in our membranes)
• Steroids - Neutral fats (triglycerides)
• Fats and oils
• Building blocks: fatty acids and glycerol
• Stored energy source - Phospholipids
• Modified triglycerides
• Building blocks: fatty acids, glycerol, phosphorus
• Cell membranes - Steroids
• Building blocks: four hydrocarbon rings
• Cholesterol
What do you know about Proteins?
- Compose 10-30% cell mass
- All contain Carbon (C), Oxygen (O), Hydrogen (H) and Nitrogen (N)
- 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 - Proteins are long chains of amino acids
• Form 3D structures
What do you know about Enzymes?
- 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)
What do you know about Nucleic acids?
- Contain Carbon (C), Oxygen (O), Hydrogen (H), Nitrogen (N), Phosphorus
(P) - Most commons nucleic acids are DNA and RNA
(—NB—)
a. Deoxyribo(se) nucleic acid (DNA) and ribo(se) nucleic acid (RNA) - Building blocks of nucleic acids: nucleotides
- 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
NB - Structure of DNA -
- T and A always bind to each other
- C and G always bind to each other
Important to know that
- T and A always bind to each other
- C and G always bind to each other
How does RNA differ from DNA?
- RNA is single-stranded
- Base Uracil is substituted for Thymine
- Deoxyribose is replaced with ribose
What is simple vs complex carbohydrates (—NBN—)
Simple: contain 1-2 sugar molecules
Complex: contain strings of sugar molecules
How do Buffering Stabilises pH
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)
