BIO 160 Chapter 2 Flashcards
Matter
anything that has mass and takes up space.
Element
any substance that cannot be broken down into simpler substances
The 4 elements that make up 96% of most cells
Oxygen, Carbon, Hydrogen, Nitrogen
Trace element
An element indispensable for life but required in extremely minute amounts.
Molecule
smallest unit of most compounds
Compound
a substance formed by chemical union of two or more elements or ingredients in definite proportion by weight
Atom
Smallest particle of an element
Electron: charge and location
Part of the atom; negative charge outside nucleus
Neutron: charge and location
Part of the atom; neutral charge in nucleus
Proton: charge and location
Part of the atom: positive charge in nucleus
Atomic number
the number of protons in the nucleus of an atom
Atomic mass
number of protons and neutrons
How to read the Periodic Table
Elements are arranged on the periodic table according to their atomic number
Octet rule
States that atoms lose, gain or share electrons in order to acquire a full set of eight valence electrons
Isotope
are alternate mass forms of an element. It has the same number of protons and electrons but differ in their number of neutrons.
Radioactive Isotope
have many uses in research and medicine. , an unstable atom in which the nucleus decays (breaks down) releasing particles and energy
Covalent bond
bond formed by the sharing of electrons between atoms
Ion
When an atom loses or gains electrons, charged
Ionic bond
the attractive force between two ions of opposite charge;
Polar molecule
molecule in which opposite ends have opposite electric charges (Water)
Hydrogen bond
weak attraction between a hydrogen atom and another atom
Chemical reaction
changes in the chemical composition of matter
Drought
a period of abnormally dry weather that changes the environment and one of the most devastating disasters
Properties of water
Cohesion; High surface tension; High heat capacity; Varying density; and Solvency
Cohesion
Water molecules stick together
High heat capacity
Water has a strong resistance to change in temperature
High surface tension
hydrogen bonding of water causes the surface to be hard to break
Varying density
Frozen water floats
Solvency
Water is a common solvent for life
Heat
a form of energy that is transferred by a difference in temperature
Temperature
a measure of how hot or cold something is
Biological significance of ice floating
Ice is less dense than water. If ice did not float, ponds, lakes, and even the oceans would freeze solid. Life in water could not survive if bodies of water froze solid.
Solution
a liquid consisting of a mixture of two or more substances
Solvent
the liquid portion of the solution
Solute
the solid portion of the solution dissolved in solvent
Acid
a chemical compound that releases H+ to a solution
Base
a compound that accepts H+ and removes them from solution
pH
describe the acidity of a solution. Mathematical way to indicate number of hydrogen ions in solution.
Buffer
substances that resist pH change. Accept H+ ions when they are in excess and donate H+ ions when they are depleted.
How to draw an atom?
Put protons and neutrons in the center as a nucleus. Then, proceed to draw circles around the nucleus and put electrons on the circles 2-8-8.
compound
substances that contain two or more elements in a fixed ratio
evaporative cooling
occurs when a substance evaporates, the liquid that is left behind cools down
