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46 terms

Bio CH 2

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matter
anything that has mass and takes up space
mass
a measure of the amount of matter in an object
element
a substance that cannot be separated or broken down into simpler substances by chemical means
atom
the smallest unit of an element that maintains the chemical properties of that element.
nucleus
an atoms central region, which is made up of protons and neutrons
proton
has a positive charge and is located in the nucleus of an atom
neutron
has no charge
atomic number
the number of protons in the nucleus of an atom
mass number
the sum of number of protons and neutrons in the nucleus of an atom
electron
a subatomic particle that has a negative charge
orbital
a region in an atom where there is a high probability of finding electrons
isotope
an atom that has the same number of protons as other atoms of the same element do but that has a different number of neutrons
compound
a substance made up of atoms of two or more different elements joined by chemical bonds
chemical bond
the attractive force that holds ions or atoms together
covalent bond
a bond formed when atoms share one or more pairs of electrons
molecule
a group of atoms that are held together by chemical forces; smallest unit of matter
ion
an atom, radical, or molecule that has gained or lost one or more electrons and has a poitive or negative charge
ionic bond
the attractive force between oppositely charged ions which form when electrons are transferred from one atom to another
energy
the capacity to do work
chemical reaction
the process by which one or more substances changes to produce one or more different substances
reactant
a substance or molecule that participates in a chemical reaction
product
a substance that forms in a chemical reaction
metabolism
the sum of all chemical processes that occur in an organism
activation energy
the minimum amount of energy required to start a chemical reaction
catalyst
a substance that changes the rate of a chemical without being consumed or changed significantly
enzyme
a type o protein or RNA molecule that speeds up metabolic reactions in plants and animals without being permnently changed or destroyed
redox reaction
the reaction in which electrons are transferred between atoms
oxidation reaction
a chemical reaction in which a reactant loses one or more electrons such that the reactant becomes more positive in charge
reduction reaction
a chemical change in which electrons are gained, either by removal of oxygen, the addition o hydrogen, or the additive of electrons
polar
describes a molecule with opposite charges on opposite ends
hydrogen bond
the intermolecular force occurring when a hydrogen atom that is bonded to a highly electronegative atom of one molecule is attracted to two unshared electrons of another molecule
cohesion
the force that holds molecules of a single material together
adhesion
the attractive force between two bodies of different substances that are in contact with eachother
capillarity
a tiny blood vessel that allows an exchange between bonds and cells in tissue
solution
a homogeneous mixture throughout which two or more substances are uniformily dispersed
solute
in a solution, the substance that dissolves the solvent
solvent
in a solution, the substance in which the solute dissolves
concentration
the amount of a particular substance in a given quantity of a mixture , solution, or ore
saturated solution
a solution that cannot dissolve any more solute under the given conditions
aqueous solution
a solution in which water is the solvent
hydroxide ion
the OH(negative) ion
hydronium ion
an ion consisting of a proton combined with a molecule of water H(3)O(positive)
acid
any compound that increases the the number of hydronium ions when dissolved in water
base
any compound that increases the number hydroxide ions when dissolved in water
pH scale
a range of values that are used to express the acidity or basicity of a system low numbers are acidic, high numbers are basic
buffer
a solution made from a weak acid and its conjugate base that neutralizes small amounts of acids or bases added to it