| A | B |
|---|
| Nucleus | The tiny, central core of an atom |
| Protons | Particles in the atomic nucleus with a positive (+) charge |
| Neutrons | Particles in the atomic nucleus with a neutral charge |
| Electrons | Moving particles in the space around the nucleus with a negative (-) charge |
| Valence Electrons | The electrons farthest from the nucleus that determine many properties of the atom. (only valence electrons are involved in chemical bonding) |
| Electron dot diagram | The symbol of the element surrounded by dots that represent each valence electron |
| Atomic number | The number of protons in the nucleus |
| Group | Elements in the same column (up and down) that share similar properties. (group is sometimes called family) |
| Period | A row across the periodic table that indicates the level the valence electrons occupy. |
| Noble gases | Group 18 (far right column), full valence levels, inert, stable |
| Halogens | Group 17, (next to the far right column) seven valence electrons (just one short of full) very reactive non-metals |
| Alkali metals | Group 1 (far left, losers), only one electron in the valence level, violently reactive |
| Electron transfer | Atoms with less than 4 valence electrons will lose them, becoming a stable but positively charge ion; atoms with more that 4 valence electrons will gain 4, becoming a stable but negatively charged ion. |
| Ion | An atom or group of atoms (polyatomic) that has become electrically charged through the gain or loss of electrons |
| Negative ion | Atom that gains electrons (-), for example, the halogens |
| Positive ion | Atom that loses electrons (+), for example the alkali metals and hydrogen |
| Ionic bond | The attraction of two oppositely charged ions, Na+ and Cl-, are attracted to each other to form neutrally charged particle, NaCl. Formed as a result of electron transfer. |
| Polyatomic ions | Ions made up of more than one atom. |
| Ionic compounds | Named by positive ion first, negative ion second. If negative ion is an element, the ending changes to ide. If negative ion is, itself, polyatomic, the ending remains unchanged. All solid at room temp. |
| Properties of ionic compounds | (example: minerals) crystal shape, high melting points, and electrical conductivity |
| Crystal | An orderly, three dimension arrangement formed by ionic compounds. |
| High melting points | When particles require the energy of high temperatures to release the high electrical attraction of their bonds |
| Electrical conductivity | When dissolved in water or molten, ionic compounds conduct electricity through their non-solid (slippery) state. (Electricity can flow as long as ions charged particles can move freely.) |
| Electron sharing | Often formed between two non-metals, electron sharing results in a more stable molecule through filling the valence levels of two or more atoms with shared electrons. |
| Covalent bond | Both atoms attract and share the valence electrons at the same time. |
| Double bonds | Covalent bond where two pairs of electrons are shared between two atoms. |
| Triple bond | Covalent bond where three pairs of electrons are shared between two atoms. In nature, triple bonds are the most that can be formed between atoms. |
| Molecular compounds | Molecules having covalently (shared) bonded atoms. Poor conductors of electricity, low melting point |
| Polar bond | A covalent bond in which electrons are shared unequally |
| Nonpolar bond | A covalent bond in which electrons are shared equally |
| Polar Molecules | The unequal sharing of electrons in polar bonds causes one side of the molecule to be slightly negative and the other side to be slightly positive. (H2O) |
| Nonpolar Molecules | Molecules containing only nonpolar bonds or containing polar bonds that cancel each other. (CO2) Nonpolar compounds do not dissolve well in water. |
| Mineral | A naturally occurring inorganic solid with a definite chemical composition and crystal structure. (memorize this!) |
| Properties of minerals | Density, crystal shape, hardness, color, how it breaks, and magnetism |
| Bond type and structure | The arrangement of particles in a mineral and the kind of bonds holding them together determine properties such as crystal shape, hardness, and the way the crystal breaks apart. |
| Ionic crystal | Smaller (broken off) crystals retain the same shape as the larger crystal due to the nature of the weak bonds along a face of ions. (minerals that show cleavage) |
| Covalent crystal | Strong bonds that cause crystals to break unevenly (minerals that show fracture). |
