What is an element?
a substance that cannot be broken down in to other substances
What is a compound?
a substance consisting of 2 or more different elements
What is a molecule?
it is formed when 2 or more atoms are joined chemically
What is an atom?
the smallest unit of matter that still retains the properties of an element
Electron?
Negative charge - negligible mass
Proton?
Positive charge - have mass
Neutron?
No charge - have mass
Atomic number?
Number of protons
Mass number/Atomic mass ?
Sum of neutrons + protons in nucleus
Chemical bonds =
attraction between 2 atoms
Polar covalent bonds =
Unequal sharing of electrons - one atom partically negative and one partially positive
Non polar covalent bonds =
Equal sharing of electrons (ex: O2/CH4)
Covalent bond =
2 atoms share outer shall electrons
Ionic bond =
Opposite charges attract
Ion =
atom/molecule with a charge as a result of gain or loss electron
Hydrogen bonds =
Weak!
Chemical reactions =
Breaking and making chemical reactions (ex: photosynthesis-cellular respiration)
Cohesion =
Molecules of the same kind tend to stick together (ex: surface tension for water)
Adhesion =
2 different kinds of molecules to stick together
Why is water so important ?
1) stronger resistance to temp changes that other liquids
2) Evaporative cooling
3) Solid (less dense than liquid form), liquid, gas
4) Protects marine life from freezing
5) Solvent of life
Solution?
liquid consisting of uniform mixture or 2 or mroe substances
Solvent ?
Dissolving agent
Solute?
Substance that is dissolved
Hydrophilic?
Polar molectures that are dissolved by water
