Chapter 2- The Chemical Basis of Life Flashcards
Atom
The smallest unit of matter that retains the properties of an element.
Proton
Subatomic particle with a single positive electric charge.
Electron
A subatomic particle with a single negative charge
Neutron
A subatomic particle which is electrically neutral.
Nucleus
An atoms central core made up of two protons and two neutrons.
Atomic number
All atoms of a particular element have the same unique number of protons. This number is the element’s atomic number.
Mass number
The number of protons and neutrons in an atoms nucleus.
Atomic mass
Approximately equal to the mass number in daltons
Isotopes
Have the same number of protons and behave identically in chemical reactions, but they have a different number of neutrons.
Radioactive isotope
An isotope in which the nucleus decays spontaneously, giving off particles and energy.
Electron shells
The circles where electrons are distributed around a nucleus
Chemical bonds
The attraction between atoms with incomplete atomic shells that have given up, accepted or shared electrons with each other.
Ionic bonds
The result of a transfer of an electron between atoms.
Covalent bonds
Caused by atoms sharing electrons between each other.
Molecule
Consists of two or more atoms held together by covalent bonds
Electronegativity
Is a measure of an atoms attraction for shared electrons.
Non polar covalent bonds
A covalent bond where the electrons are shared equally because the atoms have the same electronegativity.
Polar covalent bond
A bond formed when atoms differ in electronegativity.
Ion
An atom or molecule with an electric charge resulting from the gain or loss of one or more electrons.
Salt
Synonym for an ionic compound.
Hydrogen bond
The bond between water molecules. Fairly weak individually but incredibly strong en masse.
Polar molecule
A molecule with an unequal distribution of charges.
Reactants
The part of a chemical equation with the arrow emerging from it.
Product
The part the arrow is pointing to.
Cohesion
The tendency of molecules of the same kind to stick together.
Adhesion
The clinging of one substance 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
Thermal energy in transfer from a warmer to a cooler body of matter.
Temperature
Measures the intensity of heat aka the average speed of molecules in a body of matter.
Evaporative cooling
When a substance evaporates and the surface of the liquid that remains behind cools down.
Solution
A liquid consisting of a uniform mixture of two or more substances.
Solvent
Any dissolving agent.
Solute
Substance that is dissolved.
Aqueous Solution
A solution in which water is the solvent
Acid
A substance that donates hydrogen ions to a solution. An acidic solution has a higher concentration of H+ than OH-
Base
A substance that reduces the hydrogen ion concentration of a solution.
pH scale
A scale used to describe how acidic or basic a solution is. The scale ranges from 0 (most acidic) to 14 (most basic).
Buffers
Substances that minimize changes in ph.
Ocean acidification
CO2 dissolving in seawater lowers the ph of the ocean in this phenomenon. It destroys sea and Coral life.
