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Matter & Energy
Chapter 2
| Term | Definition |
|---|---|
| matter | anything that occupies space and has mass(weight) |
| elements | fundamental units of matter |
| subatomic particles | nucleus,protons,neutrons,orbiting the nucleus,electrons |
| atomic number | equal to the number of protons that the atoms contains |
| atomic mass number | sum of the protons & neutrons |
| isotopes | atoms of the same elements with the same number of protons and the same atomic number -vary in # of neutrons |
| radioactivity | radiosotope,heavy isotope,tends to be unstable,decomposes to more stable isotope |
| radioactivity | process of spontaneous atomic decay |
| molecule | two or morre atoms of the same elements combined chemically |
| compound | two or more atoms of different elements combined chemically |
| chemical reaction | atoms are united by chemical bonds atoms dissociate from other atoms when chemical bonds are broken |
| electrons and bonding | electrons occupy energy levels called electrons shells electrons closely to the nucleus are most strongly attracted each shell has distinct properties the number of electrons has a upper limit |