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Chemistry
Chemstry for middle school
Term | Definition |
---|---|
electron cloud | area around the nucleus where electrons are found |
valence electrons | electrons on the outer level of an atom |
atom | building blocks of matter |
atom | smallest part of an element |
matter | made up of atoms |
subatomic particles | protons, neutrons and electrons |
subatomic particles | particles that are smaller than an atom |
protons | postiviely charged particles in the nucleus |
neutrons | neutral particles in the nucleus |
electrons | negatively charged particles in the nucleus |
element | simplest substance made up of only one type of atom |
compound | made up of 2 or more elements |
molecule | groups of atoms bonded together |
hydrogen | lightest element |
Physical change | a change in properties that is reversible |
Chemical change | a non reversible change in which a new substance is made |
atomic number | number of protons in an atom |
chemical formula | shortcut way to write a molecule using subscripts and coefficients |
subscripts | Small number that comes after a symbol that tells how many atoms of an element |
coefficient | large number in front of a chemical formula that tells how many molecules |
exothermic | reaction that gives off heat |
endothermic | reaction that absorbs heat (feels cold) |
chemical reaction | atoms rearrance to make a new substance |
chemical equation | using formulas to show what happens in a chemical reaction |
Law of conservation of matter | no atoms/matter are created or destroyed in a chemical reaction. Atoms are rearranged. |
Law of conservation of matter | mass of reactants = mass of products |
reactants | chemicals on the left side of an equation that are mixed together |
products | chemicals on the right side of an equation that are made in a reaction |
electron shell | Orbits or paths where electrons travel around the nucleus |
electron level (same thing) | electron shell (same thing) |