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6th Unit 3
Elements and Reactions
Term | Definition |
---|---|
Electron | a particle with a negative electrical charge. |
Nucleus | the center of an atom |
Proton | a positively charged particle inside an atom’s nucleus. |
Neutron | a particle that is found in the nucleus of an atom and has no electrical charge. |
Electron cloud | an area where electrons arranged in energy levels travel around an atom’s nucleus. |
Element | a pure substance that cannot be broken down into simpler substance. |
Atomic number | the number of protons in an atom of an element. |
Average atomic mass | the average mass of the atoms of an element. |
Periodic table | a chart that shows the elements in order of increasing atomic number. |
Compound | a substance formed by the chemical combination of two or more elements. |
Exothermic reactions | a chemical reaction that releases energy. |
Endothermic reaction | a chemical reaction that absorbs energy. |
Rate of reaction | the measure of how fast a chemical reaction occurs. |
Catalyst | a substance that speeds up a chemical reaction but is not used up itself or permanently changed. |
Enzyme | a catalyst that speeds up chemical reactions in your body. |