Advanced Biology Unit 1 Concept 2

Matter

Anything that has mass and occupies space; composed of atoms

Atom

The smallest part of an element( think PT) that stills has the properties of that element

C (carbon), H (hydrogen), O (oxygen), N (nitrogen), P (phosphorus), S (sulfur)

6 elements necessary for life

Cell

most basic unit of life

Protons

(postive) in the nucleus

Neutrons

(neutral) in the nucleus

Electrons

(negative) in the surrounding electronic cloud

Atomic Number

number of protons

Isotope

2 or more forms of the same element (thus the same number of protons) with different numbers of neutrons

Group number on periodic table

how many valence electrons an atom has (Groups = columns on the periodic table)

Period number on periodic table

how many energy levels an atom has (Periods = rows on the periodic table)

Compound

2 or more atons of different elements bonded together

Molecule

2 or more atoms covalently bonded together

Covalent bonds

nonmetallic atoms share electrons

Ionic bonds

electrons are transferred from a metal to a nonmetal

Cation

an atom loses an electron, it become more positively charged

Anion

an atom gains an electron, it becomes more negatively charged

Polar

Unequal distribubution of charges; One side is more positive; One side is more negative; Dissolves in water

Nonpolar

No separation of charge (no positive or negative poles are formed); Does not dissolve in water

Water molecule interactions

• The partially pos hydrogen atom is attracted to the partially neg oxygen atom of a DIFFERENT water molecule

• This attraction is a hydrogen bond

• Stronger covalent bonds hold the water molecule together internally

• Weaker hydrogen bonds hold different water molecules together externally

Cohesion, adhesion, high specific heat, less dense as a solid

Properties of water

Coheision

The attraction between molecules of the same substance; Tendency of molecules of the SAME “kind” to stick together; Causes HIGH surface tension

Surface tension

Measure of how difficult it is to to stretch or break the surface of a liquid/resist an external force

Adhesion

The type of attraction that happens between two different molecules; forms stronger bonds than cohesion

High specific heat

Water has to absorb more hear energy to increase overall temperature compared to other compounds; elps to regulate cell temperatures in organisms

Less dense as a solid

Solid water (ice) is less dense than liquid water, it floats in liquid water

Solution

uniform mixture of two or more substances

Solute

what gets dissolved

Solvent

does the dissolving

Hydrophilic

Has an affinity for water; Water “loving”; Usually dissolves easily in water

Hydrophobic

Does not have an affinity for water; Water “fearing”; Does NOT dissolve in water