Chapter 2; Vocab Questions Flashcards
The Chemical Context of Life
Matter
Which is anything that takes up space and has mass.
Element
A substance that cannot be broken down to other substances by chemical reactions.
Molecule
Two or more atoms held together by covalent bonds.
Compound
A substance consisting of two or more different elements combined in a fixed ratio.
Essential Elements
An organism needs to live a healthy life and reproduce.
Atom
The smallest unit of matter that still retains the properties of an element.
Neutron
Electrically neutral.
Proton
One unit of positive charge.
Electron
One unit of negative charge.
Atomic Number
Number of protons.
Atomic Mass
Total mass of an atom.
Mass Number
The total number of protons and neutrons in the nucleus of an atom.
Isotopes
Different atomic forms of the same element.
Electron Shell
A characteristic average distance and energy level.
Valence Electron
Outer electron.
Covalent Bond
The sharing of a pair of valence electrons by two atoms.
Nonpolar Covalent Bond
In a covalent bond between two atoms of the same element, the electrons are shared equally because the two atoms have the same electronegativity.
Polar Covalent Bond
When an atom is bonded to a more electronegative atom, the electrons of the bond are not shared equally.
Ion
two resulting oppositely charged atoms or molecules.
Ionic Bond
Because of their opposite charges, cations and anions attract each other.
Hydrogen Bond
Noncovalent attraction between a hydrogen and an electronegative atom.
Chemical Reaction
The making and breaking of chemical bonds, leading to changes in the composition of matter.
Cohesion
The hydrogen bonds hold the substance together.
Adhesion
The clinging of one substance to another.
Solution
A liquid that is a completely homogeneous mixture of two or more substances.
Solute
The substance that is dissolved.
Solvent
The dissolving agent of a solution.
Hydrophobic
To repel water.
Hydrophilic
Any substance that has an affinity for water.
Acid
Is a substance that increases the hydrogen ion concentration of a solution.
Base
A substance that reduces the hydrogen ion concentration of a solution.
pH
A solution is defined as the negative logarithm of the hydrogen ion concentration.
Buffer
A substance that minimizes changes in the concentration of H+ and OH- in a solution.
