Essentials of Biology: Chapter 2

Hydrogen bond

Bond that exists between water molecules

Atom

Basic unit of matter

Atomic Number

Number of protons in an atom

Atomic Mass

Number of protons and neutrons in an atom

Isotopes

atoms of the same element, but have a different amount of neutrons

Cohesion

Attraction between particles of the same substance (water→ hydrogen bond)

Adhesion

Attraction between two different substances

Substrate

The substance on which an enzyme acts

Polar

Unequal sharing of electrons

Valence Electrons

Electrons in the outermost orbital of an atom

Covalent bond

Created due to sharing of electrons

Ionic bond

Created due to transferring of electrons

Nucleus

contains Protons and Neutrons

Matter

anything that occupies space and has mass

Element

a substance that cannot be broken down into other substances

Molecule

group of 2 or less atoms bonded together

Compound

Molecule containing 2 or more elements in a fixed ration

Mixture

2 or more elements mixed in varying rations

Solution

a liquid homogenous mixture of 2 or more elements

Solvent

the dissolving agent

Solute

the substance that is dissolved

Atomic Number

number of protons, same for all atoms of particular element, unique for each element

Mass Number

sum of protons and neutrons

Ion

an atom that has gained or lost an electron

Octet rule

atoms are reactive until they have 8 electrons in each shell

Covalent Bonds

Electron pairs are shared

Nonpolar

both atoms exert equal pull on the shared electrons

Reactants

Chemicals being changed by a reaction

Products

Chemicals produced by a reaction

Buffer

Substance that resists changes in pH by accepting or donating H+ ions

pH Scale

Measurements of the H+ ion/OH- concentrations

3 subatomic particles and their charges

protons (+), electrons (-), neutrons (0)

Universal solvent

Property of water that allows it to dissolve nutrients and carry them through the body

Electron Shell

Models that show the energy level of electrons

electronegativity

The affinity for electrons in a covalent bond

Hydrophobic

"Water fearing substances" like oil. Repels water usually as a result of non polarity

Hydrophillic

"Water loving substances" like salt. Attracted to water usually due to polar properties.