| A | B |
|---|
| matter | objects that have mass and take up space |
| atoms | the "building blocks" of matter |
| elements | substances made of only one particular type of atom |
| protons | particles in the center of an atom with positive electrical charges |
| neutrons | particles in the center of an atom without an electrical charge |
| electrons | very tiny particles that move outside the center of an atom with a negative electrical charge |
| electron cloud | completely surrounds the atom's nucleus |
| nucleus | composed of positively charged particles and electrically neutral particles |
| mass number | equal to the number of protons and neutrons in one atom of an element |
| atomic number | equal to the number of protons in an atom's nucleus |
| isotopes | atoms of the same element with different numbers on neutrons in their nucleus |
| molecule | simplest unit of a compound; made of combined atoms |
| compound | type of matter with properties that are different from the properties of each of its elements |
| chemical properties | how one substance changes when it reacts with other substances |
| ions | atoms that have lost or gained electrons |
| mixture | a combination of different substances, but each retains its own properties |
| solution | a type of mixture in which one substance is dissolved into another substance |
| physical properties | can be observed without changing a substance into a new substance |
| density | the mass of an object divided by its volume |
| physical states of matter | solid, liquid, gas, and plasma |
| solid | atoms or molecules are in a fixed position relative to each other |
| liquid | atoms or molecules are strongly attracted to each other, but are free to move |
| gas | atoms or molecules can move freely and independently from each other |
| plasma | composed of ions and electrons moving freely; most common state of matter in the universe |
