Download Biochemistry Introduction day 1

Biochemistry Introduction
Atoms and Their Composition
Atoms = the smallest part of an element that still retains the identity and properties of the element
•
Atoms are made up of even smaller particles : sub-atomic particles
+
•
•
Protons –
Neutrons –
1amu
1amu
positive charge
neutral (no charge)
•
Electrons –
0amu
negative charge
-
How do we determine the numbers of sub atomic particles of an element?
•
In a neutral atom, there are equal numbers of protons and electrons.
•
The Atomic number tells you the number or protons and electrons.
•
Neutrons = Mass number – Atomic number
Isotopes
Isotopes: Atoms of an element that have the same number of protons but a different number of
neutrons.
Ex: Oxygen usually has 8 neutrons but 9 and 10 neutrons can be found in some oxygen atoms.
 Some isotopes are unstable in the nucleus which makes it more likely to decay and
release energy. This is RADIO ACTIVITY (radioisotopes)
Modern Atomic Theory
•
matter is made up of particles called atoms, made up of protons, electrons and neutrons
•
the atom of one element cannot be converted into the atoms of any other element by a
chemical reaction
•
atoms of one element have the same properties such as mass and size ( and not the same as
other atoms)
•
atoms of different elements combine in specific proportions to form compounds
https://www.youtube.com/watch?v=FSyAehMdpyI
Chemical Compounds and Bonding
•
Chemical bonding is when there is an interaction between the valence electrons of atoms.
•
IONIC BONDING: When 2 atoms EXCHANGE electrons; one atom loses its valence electron(s) and
one atom gains valence electrons(s).
•
This usually occurs between a METAL and a NON-METAL.
•
COVALENT BONDING: When each atom contributes one or more electrons to the bond. The
electrons are shared between the atoms. This occurs between 2 NON-METALS.
•
OCTECT RULE: An atoms bond aims to achieve a more stable electron configuration.
Property
Ionic Compound
Covalent Compound
State at room temperature
Crystalline solid
Liquid, gas, solid
Melting point
High
Low
Electrical conductivity as a liquid
Yes
No
Solubility in water
Most have high solubility
Most have low solubility
Conducts electricity when dissolved in
water
Yes
No usually
Ionic Bonding
Non-Metals
Metals
Bond between a metal and non-metal involving the transfer of electrons resulting in the formation of
two ions (cation & anion)
Sodium Chloride –
 Sodium loses valence electron to become cation

Chlorine gains electron to become anion

compound is held together by attractive forces
Covalent Molecules
SHARE
Carbon Dioxide
 oxygen and carbon share valence electrons to achieve a
full outer shell (stable octet)
How to predict the type of bond…
Electronegativity – a measure of the atom’s ability to attract electrons (how badly does the atom want electrons)
Use the electronegativity values given to predict the type of bond that is formed.
Chemists consider bonds with an electronegativity difference that is greater than 1.7 to be ionic,
Bonds with an electronegativity difference that is less than 1.7 to be covalent
Chemical Equations
Chemical Reactions: when elements and compounds interact with each other to form new substances.
Reactant: A substance that undergoes a chemical reaction.
Product: A substance formed from chemical reaction.
Chemical Equations: Communicate what is happening in a chemical reaction. It can be done in a word
equation or chemical equation.

Reactants
Reactant A + Reactant B 
Products
Product
Na(s) + Cl2(g)  2NaCl(s)
Types of Reactions
Synthesis Reaction
• A + B  AB
• Na + Cl2  2NaCl
Decomposition Reaction
• AB  A + B
• 2H2O  2H2 + O2
Single Displacement Reaction
• A is a metal: Negative Switch
• A + BC  BA + C
• Cl2 + CaBr2  CaCl2 + Br2
•
•
•
A is a Non-metal: Positive Switch
A + BC  AC + B
Zn + Fe(NO3)2  Zn(NO3)2 + Fe
Double Displacement
•
•
AB + CD  AD + CB
NaCl + AgNO3  AgCl + NaNO3
Neutralization:
• Acid + Base  Salt + Water
• HCl + NaOH  NaCl + H2O
Combustion
• Carbon Fuel + Oxygen  carbon Dioxide + Water
• Ch4 (g) + 2O2(g)  CO2(g) +2H2O(g)
Common Acids & Bases
Properties of Acids & Bases
Observable properties
•
Acids taste sour and change colour when mixed with specific indicators (turn blue litmus red)
•
Bases taste bitter, feel slippery and change colour when mixed with specific indicators (turn red
litmus blue)
Conductivity in Solution
•
aqueous solutions of acids and bases conduct electricity
Bronsted-Lowry Theory of Acids & Bases
An acid is a substance from which a proton (H+) can be removed (donor)
A base is a substance that can remove a proton (H+) (acceptor)
According to Bronsted-Lowry, an acid-base reaction involves the transfer of a proton