BIO1511 Chapter 2 Flashcards

Flashcards covering the chemical basis of life, including elements, atoms, compounds, chemical bonds, properties of water, and acids and bases.

Matter

Anything that occupies space and has mass.

Element

A substance that cannot be broken down into simpler substances by ordinary chemical means.

Compound

A substance comprised of two or more elements in a fixed ratio.

Trace elements

Elements present in minute quantities but are still vital for health (e.g., iron, iodine).

Atom

Smallest unit of matter that retains properties of an element.

Proton

Positively charged subatomic particle.

Electron

Negatively charged subatomic particle.

Neutron

Electrically neutral subatomic particle.

Nucleus

Central core of the atom.

Atomic number

The number of protons in an element.

Mass number

The sum of the number of protons and neutrons in the nucleus.

Atomic mass

Approximately equivalent to the mass number.

Isotope

A version of an element with a different mass number (different number of neutrons).

Radioactive isotope

An isotope in which the nucleus decays spontaneously, giving off particles and energy (unstable).

Chemical bonds

Attractions causing atoms to remain close together.

Covalent bond

Atoms share electrons between them (this allows them to complete their outer shells).

Ionic bond

Transfer of electrons between atoms.

Molecule

Two or more atoms held together by covalent bonds.

Electronegativity

Measure of an atom’s attraction for shared electrons.

Nonpolar covalent bonds

Electrons are shared equally between atoms because of the same or similar electronegativity.

Polar covalent bonds

Electrons are drawn more closely to the more electronegative atom, which then has a partial negative charge (and the other has a partial positive charge).

Hydrogen bond

A weak bond between a partially positive hydrogen atom and a partially negative atom (for example, oxygen) in different molecules.

Chemical reaction

The breaking of existing bonds and formation of new bonds.

Reactants

The starting material in a chemical reaction.

Products

The material resulting from the chemical reaction.

Cohesion

The tendency for molecules of the same kind to stick together.

Adhesion

One substance clinging to another.

Surface tension

A measure of how difficult it is to stretch or break the surface of a liquid.

Thermal energy

The energy associated with the random movement of atoms and molecules.

Heat

Transfer of thermal energy from a warmer to a cooler body of matter.

Temperature

Intensity of heat (speed of molecules).

Evaporative cooling

When a substance changes from a liquid to a gas and the remaining liquid left behind cools down (the molecules with the highest energy leave).

Solution

A liquid with a uniform mixture of two or more substances.

Aqueous solution

A solution in which water is the solvent.

Solvent

The dissolving agent (the liquid in which something is dissolved).

Solute

The substance being dissolved.

Acids

Contribute additional H+ ions to a solution.

Bases

Reduce H+ ion concentration and result in a higher OH- concentration.

pH scale

A scale that measures how acidic or basic a solution is.