The Chemistry of LifeThe Chemistry of Life

• Relate the particle structure of an atom to identify elements.

• Relate the formation of covalent and ionic bonds to the stability of atoms

• Distinguish mixtures and solutions

• Define acids and bases and relate their importance to the biological systems

ObjectivesObjectives

• All matter is made of mass

• Atoms are the smallest particle of an element that cannot be broken down to anything smaller without losing its properties as an element

ChemistryChemistry

Elements…Elements…

• Are pure substances that cannot be broken down into smaller particles by ordinary chemical means

Atom-Atom-1. 1. Contains 3 subatomic Contains 3 subatomic

particles:particles:Charge Location Mass

a) Proton + Nucleus 1 amu

b) Neutron 0 Nucleus 1 amu

c) Electron - Orbital 0 amu

• 1 amu- Atomic Mass Unit• 1 amu= 1x10 -24 g• 0 amu= 1x10 -28 g

AtomAtom 2. 2. Locations in an Atom:Locations in an Atom:• A) Nucleus: located in the center of an atom.

Contains the protons and neutrons• B) Orbital (shell): Path around the nucleus

that contains electron(s)

• -The table of all known elements in their non-reacting state.

• Position in the table indicates certain information or properties about the element• Ex) non-metals are located more on the right

of the table

Periodic TablePeriodic Table

• Number in each box that increases by 1 when the table is read left to right is the atomic number

• The other number found in the box (usually larger than the atomic number and is a decimal) is the atomic mass

3 Rules3 Rules1. Atomic number =

# of protons

2. # of protons= # of electrons in a non-reacting atom

3. Atomic Mass = #of protons + # of neutrons

• Each atom has a set number of orbitals in a non-reacting state and each orbital can hold a certain number of electrons

OrbitalsOrbitals

1. 1st orbital can have at most 2 electrons

2. 2nd orbital can have at most 8 electrons

3. 3rd orbital can have at most 8 electrons

• Last element in each row of the periodic table has a full outer orbitalEx) HE- atomic #2 has 2

electrons

• Atoms in a non-reacting state are neutral (# protons=# of electrons)

IsotopesIsotopes• Naturally occurring

atoms with the same # of protons and electrons but a different number of neutrons (different mass)

• Usually radioactive (unstable)- used in medicine and dating objectsEx)

• 1H-mass 1 amu (Protium) normal hydrogen

• 2H- mass 2 amu (Deuterium) isotope of hydrogen

• 3H- mass 3 amu (Tritium) isotope of hydrogen

Orbital DiagramsOrbital Diagrams

• Diagrams used to show placement and number of subatomic particles found in an atom of an element

(Helium and Magnesium examples on board)

IonsIons

• Ions are atoms with a net electrical charge• Atoms with a full outer orbital are called

stable and will not react with other atoms

(Fluorine and Aluminum examples on board)

• Naturally occurring stable atoms are all in the last columnof the periodic table and are called noble gases

• Ex) He, Ne, Ar, etc.

• Naturally all other atoms strive to become stable and to do this they need to gain or lose electrons which will make the atom charged

BondsBonds

• When atoms become stable by losing or gaining electons the tend to form bonds or attractions with other atoms

• There are 3 major types of bonds: ionic, covalent, and hydrogen

1) Ionic Bonds1) Ionic Bonds

• Bond formed between 2 ions of opposite charges• Ex) Na- 2, 8, 1 electrons in its orbital• Ex) Cl- 2, 8, 7 electrons in its orbital• Na needs to lose 1 electron to become stable• Cl needs to gain 1 electron to become stable

Na +1 -----x---- Cl-1 NaCl join in an ionic bond forming table salt

• Ionic bonds tend to be strong but can be easily broken when put in water

(draw picture)

2) Covalent Bonds2) Covalent Bonds

• Bond formed by atoms sharing electrons• Ex) H- 1proton, 1electron, 0neutrons

(draw picture)• Covalent bonds formed by atoms sharing electrons

equally is called a non-polar covalent bond

Ex. Cl 17 protons, 17 electrons, 18 neutrons

H- 1 proton, 1 electron, 0 neutrons

(draw picture)

• Covalent bond formed by atoms sharing electrons unequally is called a polar covalent bond

• Covalent bonds are shown by lines between the atoms

• Ex. H-H, H-Cl

• Each line represents one pair of shared electrons

• Oxygen needs 2 electrons to fill outer orbital

O=O called double covalent bond

Non-polar due to atoms sharing electrons equally

• Nitrogen needs 3 electrons to fill an outer orbital

• N N is called a triple covalent bond• Non-polar due to atoms sharing electrons equally

• Carbons need 4 electrons to fill the outer orbital(draw picture)

3) Hydrogen Bonds3) Hydrogen Bonds

• Bond formed between 2 water molecules• Not formed directly due to atoms trying to

become stable• Hydrogen bond is very weak and is constantly

made and broken

(draw picture)

Effects of the Hydrogen bondEffects of the Hydrogen bond

a) Surface tension: Bond holds together separate H2O molecules. (water insects and paper clip)

b) Capillary Action: allows H2O Molecules to “defy” gravity and move up very small tubes using a combination of cohesion and adhesion. (plants use this motion to get water up from roots)

c) Resistance to Temperature Change: very high resistance. Keep bonds of H2O from freezing too quickly and heating up too quickly

d) High Vaporization Temperature: a high temperature is needed to evaporate water. Will take a lot of energy (heat) from the sun or other source.

e) Lower Density in Solid Form than in Liquid Form: ice floats as H2O starts freezing, molecules move closer together becoming more dense (normal), but at about 4oC molecules start spreading out to accommodate the hydrogen bonds making it less dense

Chemical ReactionChemical Reaction

• Process of breaking bonds, creating bonds, or a combination of both and at the same time rearranging atoms

(draw example)

Chemical FormulaChemical Formula

• Method used to indicate # of atoms of each element in a molecule.• Ex) H20, CO2,

CH4, C6H12O6

Structural FormulaStructural Formula

• Method used to indicate # of atoms of each element the shape of the molecule, and type of bonds

(draw example)

Balancing Chemical Reaction EquationsBalancing Chemical Reaction Equations

• An equation is balanced when it has the same number of atoms of each element on each side of the arrow

• Ex. H2 + Cl2 HCl

• Not balanced- 2 atoms of H and 2 atoms of Cl on left and only one of each on the right.

Rules to Balancing EquationsRules to Balancing Equations

1. Cannot change subscripts

Ex. I need 4 atoms H to balance and equation

H2 cannot change this number to 4 (H4 NO WAY)

Rules to Balancing EquationsRules to Balancing Equations

2. Can only change coefficient and it effects the whole molecule

Ex. I need 6 atoms of hydrogen to balance an equation

1 H2 3H2 3 H20 will give you 6 atoms of H+3 of oxygen

Rules to Balancing EquationsRules to Balancing Equations

3. Cannot put a coefficient in the middle of a molecule

Ex. I need 2 atoms of oxygen to balance an equation

H20 I could not do the following H220

I could do 2 H20