BIO 101 Chapter 2A Obj jc

Matter

anything that has mass and takes up space

Energy

Ability to do work or create a change

Elements

pure substance consisting of atoms, cannot be broken down into other elements by chemical means

Three sub-atomic particles

Protons, Neutrons, Electrons

Amount of elements essential to life

25

Atoms

smallest piece of an element that retains the characteristics of the element, individual building blocks of elements

Electron: charge, mass, location

Sub-atomic particle with a small mass (~0), negative charge, located surrounding the nucleus

Proton: charge, mass, location

Sub-atomic particle with a larger mass (1), positive charge, located in the nucleus

Neutron: charge, mass, location

Sub-atomic particle with a larger mass (1), no charge, located in the nucleus

Atomic Number

number of protons in an atom

Mass Number

protons and neutrons in an atom

Ions

Atom or element that gained or lost electrons

Isotopes

Alternate form of an element based on number of neutrons

Atomic Weight

Average mass of all the different types of that specific element

Radioactive Isotope

unstable isotopes that emit radiation as their nucleus decays

Molecules

Two or more combined atoms

Compound

two or more different elements that are chemically combined in a fixed ratio

Orbitals

a 3 dimensional region around an atom’s nucleus where an electron is most likely to be found

Amount of electrons that can be held in each orbital

2

Energy shells

Group of electron orbitals that share the same energy level

Amount of electrons that can be held in each energy shell

Maximum number of electrons in an energy shell = 2n^2

Position of an electron in relation to energy level

Amount of energy increases as you move away from the nucleus

Valence Shell

Outermost shell that has electrons

Valence Electrons

Electrons in the outermost shell of an atom

Electronegativity

Ability to attract electrons, affinity for electrons

Chemical Bonds

Connection between atoms

Three types of chemical bonds in living systems

Covalent, ionic, hydrogen

Covalent Bond definition

Sharing of electrons

Ionic Bond definition

Transfer of electrons

Covalent bond: location and relative strength

intramolecular, stronger

Ionic bond: location and relative strength

intramolecular, stronger

Hydrogen bond: location and relative strength

intermolecular, weaker

Polar Covalent Bond

Unequal sharing of electrons

Non-Polar Covalent Bond

Equal sharing of electrons

What are the five life-supporting properties of water?

cohesive and adhesive
many substances dissolve in water
water regulates temperature
water expands as it freezes
water participates in life's chemical reactions

Cohesion

Attraction between water molecules

Adhesion

Attraction of water molecules with other substances

Solvent

Chemical in which other substances dissolve

Solute

Chemical that dissolves in a solvent

Solution

Mixture of solute and solvent

Hydrophobic

Water fearing, nonpolar substances

Hydrophilic

Water loving, polar or charged substances

Chemical Reactions

Breaking and forming of bonds

Reactants

Starting material in a chemical reaction

Products

Result of a chemical reaction

Balanced equation of photosynthesis

6CO2 + 6H2O = C6H12O6 + 6O2

pH

Power of hydrogen, H+

pH Scale

Measurement of how acidic or basic a solution is, measurement of H+ concentration/hydrogen

Equation for disassociation of water

H20 = OH^- + H^+

Acid

Molecule that adds H^+, hydrogen ions

Base

Molecule that adds OH^-, hydroxide ions