BIOL 170 Ch 2 Chemistry of Life

Atom

The smallest unit of matter, consisting of protons, electrons, and neutrons.

Element

A substance made of only one kind of atom.

Atomic Number

The number of protons in an atom.

Average Atomic Mass

The total number of protons and neutrons in an atom.

Isotopes

Variants of elements that have the same number of protons but different numbers of neutrons.

Protons

Positively charged particles found in the nucleus of an atom.

Electrons

Negatively charged particles that orbit the nucleus of an atom.

Neutrons

Neutral particles found in the nucleus of an atom.

Valence Shell

The outermost shell of an atom that determines its chemical reactivity.

Octet Rule

The principle that atoms are most stable when they have eight electrons in their valence shell.

Ionic Bonding

A type of chemical bond formed through the transfer of electrons from one atom to another.

Cation

A positively charged ion that loses one or more electrons.

Anion

A negatively charged ion that gains one or more electrons.

Covalent Bonding

A type of chemical bond formed when two atoms share electrons.

Non-Polar Covalent Bonds

Bonds between two nonmetals with similar electronegativity that share electrons equally.

Polar Covalent Bonds

Bonds between nonmetals with different electronegativity that share electrons unequally, resulting in partial charges.

Hydrogen Bonds

Weak attractions between the partially positive end of one polar molecule and the partially negative end of another.

Hydrophilic

Substances that are attracted to water.

Hydrophobic

Substances that repel water.

Organic Molecules

Compounds primarily made of carbon, essential for life.

Inorganic Molecules

Compounds that do not primarily consist of carbon.

Water

An inorganic molecule that makes up 60-80% of the mass of the human body and is a universal solvent.

Specific Heat

The amount of heat required to change the temperature of a substance.

Heat Capacity

The ability of a substance to absorb heat.

Heat of Vaporization

The amount of energy required for a substance to transition from liquid to gas.

Carbohydrates

Organic molecules composed of carbon, hydrogen, and oxygen, serving as energy storage and structural support.

Monosaccharides

Simple sugars that are the monomers of carbohydrates.

Disaccharides

Carbohydrates formed by the union of two monosaccharides through dehydration synthesis.

Oligosaccharides

Short chains of monosaccharides (fewer than 12).

Polysaccharides

Long chains of monosaccharides (more than 12) that serve as energy storage or structural components.

Glycosidic Bonds

Bonds formed between monosaccharides during dehydration synthesis.

Starch

A polysaccharide that serves as energy storage in plants.

Glycogen

A polysaccharide that serves as energy storage in animals.