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gallo chap 17 vocab
| Question | Answer |
|---|---|
| atom | the smallest particles of an element that can be identified with that element. Consists of protons and neutrons in a nucleus surrounded by electrons. |
| element | a substance made of only one kind of atom. |
| Brownian motion | the peretual random movement of microscope particles suspended in a fluid medium. |
| molecule | the smallest particle of a substance consisting of two or more atoms of the same or different elements bonded together. |
| compound | a chemical substance made of atoms of two or more different elements combined in a fixed proportion. |
| chemical formula | a description that uses numbers and symbols of elements to describe the proportions of elements in a compound or reaction. |
| nucleus | the positively charged center of an atom, which contains protons and neutrons and had almost all the mass of the entire atom only a tiny fraction of the volume. |
| nucleons | the principal buliding block of the nucleus; a neutron or a proton. |
| neutrons | an electrically neutral particle that is one of the two kinds of particles that compose an atomic nucleus. |
| protons | a positively charged praticle that is one of the two kinds of particles found in the nucleus of an atom. |
| atomic number | number of protons in the nucleus of an atom |
| ion | an atom (or a group of atoms bound together) with a net electric charge, which is due to the loss or gain of electrons. |
| shell model of the atom | a model in which the electrons of an atom are pictured as grouped in concentric shells around the nucleus. |
| periodic table | a chart that lists elements by atomic number and by electron arangements, so that elements with similar chemical properties are in the same column. |
| plasma | a fourth phase of matter in addition to solid. liguid, and gas. In the plasma phase, which exsists mainly at high temperature, matter consists of positively charged ions and free electrons. |