Biology Chapter 2: The Chemical Basis of Life

Any of the more than 100 known substances that cannot be separated into simpler substances by chemical reactions.

That which has mass and occupies space.

The property of a body that causes it to have weight in a gravitational field.

<p>A substance consisting of two or more different elements combined in a fixed ratio.</p> Signup and view all the answers

<p>Elements required by an organism, but only in minute quantities.</p> Signup and view all the answers

<p>The smallest unit of matter that still retains the properties of an element.</p> Signup and view all the answers

<p>Electrically neutral.</p> Signup and view all the answers

<p>Each proton has 1 unit of positive charge.</p> Signup and view all the answers

<p>Each electron has 1 unit of negative charge.</p> Signup and view all the answers

<p>At the center of an atom, the atomic nucleus has protons and neutrons tightly bound together.</p> Signup and view all the answers

<p>A unit of measurement for the mass of atoms and subatomic particles.</p> Signup and view all the answers

<p>The number of protons, unique to each element, in an atom.</p> Signup and view all the answers

<p>1</p> Signup and view all the answers

<p>They have the same number of protons in their nuclei.</p> Signup and view all the answers

<p>The sum of protons and neutrons in the nucleus of an atom.</p> Signup and view all the answers

<p>Subtract the atomic number from the mass number.</p> Signup and view all the answers

<p>Different atomic forms of the same element.</p> Signup and view all the answers

<p>A radioactive isotope, one where the nucleus spontaneously decays.</p> Signup and view all the answers

<p>The capacity to cause change.</p> Signup and view all the answers

<p>Energy that a body possesses by virtue of being in motion.</p> Signup and view all the answers

<p>Electrons are found in different electron shells, with the energy levels increasing as the shells are further away from the nucleus.</p> Signup and view all the answers

<p>The electrons that exist on the outermost shell of an atom.</p> Signup and view all the answers

<p>The outermost electron shell of an atom.</p> Signup and view all the answers

<p>The distribution of electrons in the atom's electron shells.</p> Signup and view all the answers

<p>The attractions between atoms.</p> Signup and view all the answers

<p>One of the strongest types of chemical bonds; it is the sharing of a pair of valence electrons by two atoms.</p> Signup and view all the answers

<p>Two or more atoms held together by covalent bonds.</p> Signup and view all the answers

<p>H:H</p> Signup and view all the answers

<p>H2</p> Signup and view all the answers

<p>H-H</p> Signup and view all the answers

<p>O=O</p> Signup and view all the answers

<p>When two atoms are so unequal in their attraction for valence electrons that the more electronegative atom strips an electron completely away from its partner.</p> Signup and view all the answers

<p>The noncovalent attraction between a hydrogen and an electronegative atom.</p> Signup and view all the answers

<p>They enable all atoms and molecules to stick to one another.</p> Signup and view all the answers

<p>H2O</p> Signup and view all the answers

<p>A formula that shows the arrangement of atoms in the molecule of a compound.</p> Signup and view all the answers

<p>A single pair of shared electrons.</p> Signup and view all the answers

<p>Two pairs of shared valence electrons.</p> Signup and view all the answers

<p>Three pairs of shared valence electrons.</p> Signup and view all the answers

<p>The attraction of a particular atom for the electrons of a covalent bond.</p> Signup and view all the answers

<p>The type of charge an atomic particle has.</p> Signup and view all the answers

<p>When one atom is bonded to a more electronegative atom, the electrons of the bond are not shared equally.</p> Signup and view all the answers

<p>When a covalent bond between two atoms of the same element and the electrons are shared equally.</p> Signup and view all the answers

<p>A charged atom.</p> Signup and view all the answers

<p>When an ion is charged positively.</p> Signup and view all the answers

<p>When an ion is charged negatively.</p> Signup and view all the answers

<p>Compounds formed by ionic bonds, also called ionic compounds.</p> Signup and view all the answers

<p>Substances that undergo a chemical reaction.</p> Signup and view all the answers

<p>A chemical substance formed as a result of a chemical reaction.</p> Signup and view all the answers

<p>A substance consisting of two or more different elements in a fixed ratio.</p> Signup and view all the answers

<p>They are different from those of its elements.</p> Signup and view all the answers

<p>Oxygen, Carbon, Hydrogen, and Nitrogen.</p> Signup and view all the answers

<p>Of the 92 elements, 20-25% are essential elements.</p> Signup and view all the answers

<p>The same as a proton, approximately $1.7 imes 10^{-24}$.</p> Signup and view all the answers

<p>Hydrogen - with 1 proton and 1 electron.</p> Signup and view all the answers

<p>The point at which reactions of reactants and products offset each other exactly.</p> Signup and view all the answers

<p>Oxygen (65%), Carbon (~20%), Hydrogen (~10%), Nitrogen (~3%), Calcium (~2%), Phosphorus (~1%).</p> Signup and view all the answers