The 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 systemsObjectives

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 Chemistry

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

Atom- 1. Contains 3 subatomic particles: Charge LocationMass a) Proton+Nucleus1 amu b) Neutron0Nucleus1 amu c) Electron-Orbital0 amu

1 amu- Atomic Mass Unit 1 amu= 1x g 0 amu= 1x g Atom2. 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 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 Rules 1.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

Orbitals 1.1 st orbital can have at most 2 electrons 2.2 nd orbital can have at most 8 electrons 3.3 rd orbital can have at most 8 electrons

Last element in each row of the periodic table has a full outer orbital Ex) HE- atomic #2 has 2 electrons Atoms in a non- reacting state are neutral (# protons=# of electrons)

Isotopes 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 objects Ex) 1 H-mass 1 amu (Protium)  normal hydrogen 2 H- mass 2 amu (Deuterium)  isotope of hydrogen 3 H- mass 3 amu (Tritium)  isotope of hydrogen

Orbital Diagrams Diagrams used to show placement and number of subatomic particles found in an atom of an element (Helium and Magnesium examples on board)

Ions 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 column of 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

Bonds 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 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 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 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 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 bond a)Surface tension: Bond holds together separate H 2 O molecules. (water insects and paper clip)

b) Capillary Action: allows H 2 O 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 H 2 O 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 H 2 O starts freezing, molecules move closer together becoming more dense (normal), but at about 4 o C molecules start spreading out to accommodate the hydrogen bonds making it less dense

Chemical Reaction Process of breaking bonds, creating bonds, or a combination of both and at the same time rearranging atoms (draw example)

Chemical Formula Method used to indicate # of atoms of each element in a molecule. Ex) H 2 0, CO 2, CH 4, C 6 H 12 O 6

Structural Formula Method used to indicate # of atoms of each element the shape of the molecule, and type of bonds (draw example)

Balancing 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. H 2 + Cl 2  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 Equations 1.Cannot change subscripts Ex. I need 4 atoms H to balance and equation H 2  cannot change this number to 4 (H 4 NO WAY)

Rules 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 H 2  3H 2 3 H 2 0  will give you 6 atoms of H+3 of oxygen

Rules 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 H 2 0  I could not do the following H 2 20 I could do 2 H 2 0