| A | B |
|---|
| element | a pure substance that can not be broken down into any simpler substances through chemical reaction |
| hydrogen and helium | __________________ and _________________ are the most common elements found in space |
| atom | the smallest unit of an element that has the properties of that element |
| nucleus | the center of an atom that has most of its mass |
| proton | the particle in the nucleus of an atom that carries one unit of positive electric charge |
| neutron | a particle in the nucleus that has no electric charge |
| electron | a particle in the space outside the nucleus of an atom that carries one unit of negative electric charge |
| molecule | a particle that contains more than one atom joined together |
| chemically reactive | _______________ _________________ elements are more likely to combine with other elements to form new substances |
| metalloids | elements with properties in between metals and non metals |
| nonmetals | elements that are dull, poor conductors, and brittle |
| atomic mass unit | Protons and neutrons have about the same mass. This mass is called an ___________ _______ _______. |
| atomic mass | If you add up the mass of all the particles in an atom, you get the atom's _______________ __________ |
| chemical formula | Molecules are described by combining letters and numbers into a __________________ ________________ |
| subscripts | Numbers in a chemical formula are known as ______________ |
| periodic table | The ____________________ _________________ was created by Dmitri Mendeleev. Each column contains elements with similar chemical properties |
| metal | a group of elements that conducts heat and electricity as a shiny luster and is flexible |
