Structure of Water and Hydrogen Bonding
Matter
Anything that takes up space and has mass, including rocks, metals, oils, gases, and organisms
Element
A substance that cannot be broken down into other substances by chemical reactions; there are 92 naturally occurring elements
Compound
A substance consisting of two or more different elements combined in a fixed ratio, such as H2O or NaCl
Essential Elements
20-25% of the 92 naturally occurring elements that are essential for survival and reproduction; CHOPN make up 96% of living matter
Trace Elements
Elements required by an organism in very small quantities
Atomic Number
The number of protons in an atom
Atomic Mass
The number of protons plus neutrons averaged over all isotopes
Valence Electrons
Electrons in the outermost shell of an atom that determine its chemical properties
Bohr Model
A model showing electrons orbiting the nucleus of an atom in defined energy levels
Lewis Dot Model
A simplified representation of an atom that shows only the valence electrons
Chemical Bonds
An attraction between two atoms resulting from the sharing or transferring of valence electrons
Electronegativity
A measure of an atom’s ability to attract electrons to itself
Covalent Bonds
Bonds formed when two or more atoms share electrons, typically between nonmetals
Nonpolar Covalent Bond
A bond where electrons are shared equally between two atoms
Polar Covalent Bond
A bond where electrons are not shared equally, resulting in partial charges
Ionic Bonds
The attraction between oppositely charged ions, typically formed between metals and nonmetals
Hydrogen Bonds
An attraction between a partially positive hydrogen atom in one polar covalent molecule and an electronegative atom in another
Polarity
The property of water that results from the unequal sharing of electrons, making it a polar molecule
Cohesion
The attraction of molecules for other molecules of the same kind, responsible for surface tension in water
Adhesion
The clinging of one molecule to a different molecule, allowing water to resist the pull of gravity in plants
Capillary Action
The upward movement of water due to cohesion, adhesion, and surface tension
High Specific Heat
The ability of water to resist changes in temperature due to hydrogen bonds
Evaporative Cooling
The process where water absorbs heat when it evaporates, cooling the surface it leaves
Density of Ice
Water expands and becomes less dense when it solidifies, allowing ice to float and marine life to survive beneath it
Solvent
A substance that dissolves other substances; water is a versatile solvent due to its polar nature
Solution
A homogeneous mixture of two or more substances, consisting of a solvent and a solute
Solute
Substance that is dissolved
Group
elements in the same vertical column have the same number of valence electrons
Period
Elements in the same horizontal row have the same total number of electron shells
Octet Rule
Elements will gain, lose, or share electrongs to complete their valence shell and become stable
Intermolecular bond
Bond that forms between molecules