Unit one water

Matter

Anything that takes up space and has mass.

Element

A substance that cannot be broken down into other substances by chemical reactions.

Compound

A substance consisting of two or more different elements combined in a fixed ratio.

Essential elements

Elements that are crucial for survival and reproduction, comprising 20-25% of naturally occurring elements. Carbon, Hydrogen, Oxygen, Phosphorus, Nitrogen

Trace elements

Elements required by an organism in very small quantities.

Atomic number

The number of protons in an atom.

Atomic mass

The total number of protons plus neutrons averaged over all isotopes.

Valence electrons

Electrons in the outermost shell of an atom that are involved in forming bonds.

Bohr Model

A model depicting electrons orbiting the nucleus of an atom, with each shell representing a different energy level.

Lewis Dot Model

A simplified representation of an atom showing only the valence electrons.

Chemical Bonds

The attraction between two atoms resulting from the sharing or transferring of valence electrons.

Electronegativity

The measure of an atom’s ability to attract electrons to itself.

Covalent bonds

Chemical bonds formed when two or more atoms share electrons.

Ionic bonds

The attraction between oppositely charged atoms (ions), typically between a metal and a nonmetal.

Hydrogen bonds

Intermolecular bonds that occur between polar covalent molecules, involving partial positive and negative charges.

Polarity

The distribution of electrical charge over the atoms involved in a bond, making water a polar molecule.

Cohesion

The attraction of molecules for other molecules of the same kind, contributing to surface tension.

Adhesion

The clinging of one molecule to a different molecule, enabling capillary action in plants.

Capillary Action

The upward movement of water due to the forces of cohesion, adhesion, and surface tension.

High Specific Heat

A property of water that allows it to resist changes in temperature due to hydrogen bonds.

Evaporative Cooling

The process where water absorbs heat when it evaporates, helping regulate temperature.

Density (floating ice)

Water expands and becomes less dense as it solidifies, allowing ice to float and enabling marine life to survive in cold water. The shape of ice crystals allow space in the middle allowing more volume mean in less density.

Solvent

The dissolving agent in a solution; water is a versatile solvent due to its polar nature.

“Like dissolves like”

A principle stating that polar solvents dissolve polar solutes and nonpolar solvents dissolve nonpolar solutes.