- All Matter in universe is composed of Atoms
- Elements are composed of only 1 type of atom.
- Atoms are mostly empty space.
- Atoms have Electrons which are very small and are negatively charged and have a negligible mass (mass = 0).
- Electrons move in orbits around the center of the atom - in relatively distinct areas called Energy Levels.(aka. Orbits or shells)
- The farther from the center an electron is the more energy it has.
- Electrons (& therefor atoms, can gain and lose energy) and do this by moving between energy levels.
- Atoms have a Nucleus which contain Protons & Neutrons.
- Protons are Positively Charged and have a mass =1
- The number of protons in an atom’s nucleus determines what element it is
- Neutrons have no charge and are therefor called Neutral and have a mass = 1.
The "basic" Atom
Summary of Subatomic Particles:
Particle | Location | Charge | Mass |
PROTON | Nucleus | +1 | 1 |
NEUTRON | Nucleus | None / Neutral | 1 |
ELECTRON | Energy Levels / orbits | -1 | ~0 |
Periodic Table Notation:
- Chemical elements are represented on the periodic table using the above format.
- The letter is an abbreviation of Element Name
- Atomic Number is the number is the number of protons the atom has. It is the number of protons an element has which determines what element it is.
- Mass number is the total mass of an atom in AMU. It is the same as the number of protons & neutrons of the element. One can calculate the number of neutrons an atom has by subtracting the atomic number (# protons) from the mass number. Mass number CAN change without changing the identity of the element.
- Atoms having the same atomic numbers and different mass numbers are called Isotopes.
Isotopes:
- Isotopes are atoms of the same element with different numbers of neutrons (mass).
- They react chemically the same as the "normal" form of the element
- They are frequently radioactive
Example Isotopes: Hydrogen
Interactions of matter:
- Atoms interact through the process of chemical bonding.
- Process is determined by the number of electrons found in the outermost energy level of an atom.
- Involves the transfer & sharing of electrons between atoms.
- ELECTRON / ENERGY LEVEL RULES:
- Atoms in a neutral state have an equal number of protons and electrons.
- Atoms "fill up" their energy levels from the lowest to the highest. Electrons rarely "skip" levels.
- The 1st Energy level can only hold 2 electrons
- The 2nd and 3rd energy levels can only hold 8 electrons
- Atoms seek to have a "full" outermost energy level. All chemical reactions happen to accomplish this
Chemical Bonds
- When a Chemical Reaction occurs atoms gain, lose or share electrons.
- Atoms always want to have their outer energy level "full" of electrons
- When an atom has a different number of protons & electrons it is called an Ion.
- If an ion has more protons than electrons - it is Positively Charged
- If an atom has more electrons than protons it is Negatively Charged.
- Atoms of opposite charge are attracted to each other.
- There are three types of chemical bonds. Ionic bonds, Covalent Bonds, & Metallic Bonds.
- Ionic bonds form when 1 atom "gives" one or more electrons to another atom.
- This results in 1 positively charged ion & 1 negatively charged ion
- Since opposite charges attract, they come together and bond
- Covalent bonds form when 2 atoms "share" one or more electrons between them.
- There are 2 types of covalent bonds:
- Non-Polar Covalent bonds form when two atoms share electrons equally
- Polar Covalent bonds form when two atoms share electrons unequally.
- Atoms can share more than 1 electron between them forming multiple bonds
- A Molecule is a group of 2 or more atoms held together by covalent bonds.
Ionic Bonding
Covalent Bonding
Summary of Ionic & Covalent Bonds
Chemical Reactions
- A Chemical Reaction = whenever a chemical bond is formed or broken.
- 2 types (sometimes 3) of substances with chemical reactants
- Reactants = Substances existing before the reaction
- Products = Substances existing after the reaction
- Catalysts = Substances which speed up the rate of a reaction
- Chemical Equations are a shorthand way of showing chemical reactions.
- Separates Products and reactants.
- Usually follow flow of energy.
- Rx’s naturally occur when they release energy
- Can however occur when energy is added.
Structural Formulas:
- Structural Formulas are used to graphically represent a chemical formula
- Useful in visualizing how chemicals react and form new ones.
- When drawing them use the following rules:
- The Periodic table abbreviation is used to represent the atoms.
- A single strait line (---) represents a single bond
- Two parallel strait lines (==) represent double bonds
- Examples:
Chemical Name | Chemical Formula | Structural Formula |
Water | H2O |  |
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