Biology: Chapter 2

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Terms in this set (...)

Atom
The smallest part of a chemical element.
Element
A chemical substance consisting of one type of atom.
Valence Electron
An electron found in the outermost orbital. Makes bonds.
Trace Element
Required by/found in an organism in small quantities. Ex.: iron, iodine, fluorine.
Neutron
A subatomic particle found in the nucleus of the atom. Has no charge.
Electron
A subatomic particle found in the orbitals of the atom. Has a negative charge
Proton
A subatomic particle found in the nucleus of the atom. Has a positive charge.
Atomic Number
Number of protons in the nucleus. Is unique to each atom.
Mass Number
The mass of the protons and neutrons (electrons have nearly no mass)
Isotope
Two or more elements that have the same number of protons but a different number of neutrons.
Ion
An atom that has either gained or lost an electron
Cation
Loses an electron, positively charged, is a metal
Anion
Gains an electron, negatively charged, nonmetal
Molecule
Substance formed by the bonding of two or more different atoms in definite ratios; ionic or covalent
Ionic Bond
Bond formed when electrons are transferred, and the resulting ions are attracted to each other. Occurs between a metal and a nonmetal.
Covalent Bond
Bond formed when electrons are shared between two atoms, usually nonmetals.
Polar Covalent Bond
Electrons are shared, but unequally
Electronegativity
Pull of the nucleus on electrons, some elements exert more pull than others.
Polarity
Difference in electrical charge on opposite ends of a molecule.
Hydrogen Bond
A bond between the oxygen of one water molecule and the hydrogen of another.
Cohesion
Water molecules sticking together.
Adhesion
Water molecules sticking to other things (forming a column)
Heat Capacity
The ability to "hold" or "store" heat.
Specific Heat
The amount of energy required to raise a substance's temperature by 1 degree Celsius.
Surface Tension
Measure of how difficult it is to stretch or break the surface of a liquid.
Solution
A mixture of two or more substances that is uniform throughout (ex. saltwater)
Solvent
Dissolving agent (water)
Solute
Substance that dissolves (salt)
Hydrophilic
Water-loving; dissolves in water
Hydrophobic
Water-hating, does not dissolve in water.
Acid
Substance that adds more H+ ions to a solution.
Base
Substance that adds more OH- ions, or removes H+ ions.
Acid Rain
Rain with a pH below 5.5.
Buffer
Solution that resists change in pH (helps make pH stay the same even if you add an acid/base).
Group
Groups are the columns in the periodic table.
Period
Periods are the rows in the periodic table.