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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 |