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Biology 101 Exam 1

Chapter 2 Terms and Definitions

Matter Any substance in the universe that has mass and occupies space.
Atoms All matter is composed of extremely small particles
Protons carries a positive (+) charge
Neutrons no charge
Electrons carries a negative (-)
Orbital Defined as the area around a nucleus where an electron is most likely to be found.
Atomic Nucleus The nucleus is the very dense region consisting of protons and neutrons at the center of an atom.
Atomic Number is the number of protons found in the nucleus of an atom and therefore identical to the charge number of the nucleus.
Element is any substance that cannot be broken down to any other substance by ordinary chemical means.
Compound When a molecule contains atoms of more than one element.
Atomic Mass Of an atom is equal to the sum of the masses of its protons and neutrons.
Isotopoes Different forms of the same element which the same number of protons but different numbers of neutrons.
Neutural Atoms Atoms with the same number of protons and electrons are electrically neutral; they have no net charge.
Ions Atoms in which the number of electrons does not equal the number of protons.
daltons The mass of atoms and subatomic particles is measured in units.
cation An atom having more protons than electrons has a net positive charge.
anion A negatively charged ion. An atom having fewer protons than electrons carries a net negative charge.
radioactive isotopes Isotopes that decay in in a fashion like radioactive decay.
radioactive decay Carbon-14 Its nucleus tend to break up into elements with lower atomic numbers. This nuclear breakup, which emits a significant amount of energy.
half-life The decay time is usually expressed. The time it takes for one-half of the atoms in a sample to decay.
Oxidation reduction A type of paired reaction in living systems in which electrons lost from one atom (oxidation) are gained by another atom (reduction). Termed a redox reaction for short.
Chemical Bonds The atoms in a molecule are joined; these bonds can result when atoms with opposite charges attract each other.
Covalent Bonds Form when two atoms share one or more pairs of valence electrons.
Created by: usn3gen