Unit one: The Chemistry of Life
Chapter 2: The Chemical Context of life
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| 7343254181 | Matter | Anything that takes up space and has mass. | 0 | |
| 7343254182 | Element | Substance that cannot be broken down to other substances through chemical reactions. Each has a symbol. 92 occurring in nature. |  | 1 |
| 7343254183 | Compound | Substance consisting of two or more different elements combined in a fixed ratio. *Characteristics different than those of its elements |  | 2 |
| 7343254184 | CHON | 4 elements essential to life | 3 | |
| 7343254185 | Trace Elements | Required by an organism only in minute quantities. | 4 | |
| 7343254186 | Atom | Smallest unit of matter that retains the properties of an element. Composed of subatomic particles. Mostly empty space. | 5 | |
| 7343254187 | Subatomic particles | Neutrons, protons, electrons. Make up atoms. | 6 | |
| 7343254188 | Proton | One unit of positive charge. Approximately one dalton. Located in nucleus. |  | 7 |
| 7343254189 | Electron | One unit of negative charge. Located outside of nucleus. | | 8 |
| 7343254190 | Atomic Nucleus | Dense core packed with protons and neutrons. |  | 9 |
| 7343254191 | Neutrons | Electrically neutral. Approximately one dalton. |  | 10 |
| 7343254192 | Atomic Number | The number of protons (which is unique to that element) and written as a subscript to left of element symbol. Also tells us number of electrons since P=E if atom is neutral |  | 11 |
| 7343254193 | Mass Number | Sum of the protons and the neutrons. An approximation of the atomic mass. |  | 12 |
| 7343254194 | Isotopes | Same number of protons, but different number of neutrons and therefore different mass. Same element. |  | 13 |
| 7343254195 | Radioactive Isotope | One in which the nucleus decays spontaneously, giving off particles and energy. Can decay to a different element. Have useful applications. |  | 14 |
| 7343254196 | Energy | Capacity to cause change | 15 | |
| 7343254197 | Potential Energy | Energy matter possesses because of its location or structure. Electrons have this based on distance from nucleus. |  | 16 |
| 7343254198 | Electron Shells | Where electrons are found, each with characteristic average distance and energy level. Electrons can change these by absorbing or losing energy. |  | 17 |
| 7343254199 | Valence Electrons | Electrons in the outermost shell. |  | 18 |
| 7343254200 | Chemical Bonds | The attraction that holds atoms together during an interaction. | 19 | |
| 7343254201 | Covalent Bond | Sharing of a pair of valence electrons by two atoms. |  | 20 |
| 7343254202 | Molecule | Two or more atoms held together by covalent bonds. | 21 | |
| 7343254203 | Single Bond | One pair of shared electrons. | 22 | |
| 7343254204 | Structural Formula | H--H. Notation which represents both atoms and bonding. | 23 | |
| 7343254205 | Double Bond | Sharing two pairs of valence electrons. | 24 | |
| 7343254206 | Valence | Bonding capacity. Equal to the number of unpaired electrons required to complete the outermost (valence) shell. | 25 | |
| 7343254207 | Electronegativity | The attraction of a particular kind of atom for the electrons of a covalent bond. |  | 26 |
| 7343254208 | Nonpolar Covalent Bond | Covalent bond in which electrons are shared equally. |  | 27 |
| 7343254209 | Polar Covalent Bond | Where one atom is bonded to a more electronegative atom and the electrons of the bond are not shared equally. |  | 28 |
| 7343254210 | Ionic Bonds | The attraction of cations and anions. The transfer of electrons creates ions which form an ionic bond. |  | 29 |
| 7343254211 | Ion | A charged atom. | 30 | |
| 7343254212 | Cation | A positively charged atom. |  | 31 |
| 7343254213 | Anion | A negatively charged atom. |  | 32 |
| 7343254214 | Ionic Compounds | Or Salts. Compounds formed by ionic bonds. |  | 33 |
| 7343254215 | Hydrogen Bond | When a hydrogen atom covalently bonded to an electronegative atom is also attracted to another electronegative atom. |  | 34 |
| 7343254216 | van der Waals Interactions | Ever changing regions of positive and negative charge that enable all atoms and molecules to stick to one another. |  | 35 |
| 7343254217 | Molecular Shape | Determines how biological molecules recognize and respond to one another. | 36 | |
| 7343254218 | Reactants | The starting materials of a chemical reaction. |  | 37 |
| 7343254219 | Products | The resulting material of a chemical reaction. | | 38 |
| 7343254220 | Chemical Equilibrium | The point at which the relative concentrations of the products and the reactants stop changing and offset one another exactly. |  | 39 |
