Atoms, Matter, Compounds

4. An atom that has gained or lost electrons, giving it a charge.
9. Compounds: Compounds mainly made of carbon and hydrogen.
10. Compounds made of carbon, hydrogen, and oxygen that provide energy.
11. The smallest unit of an element.
12. Anything that has mass and takes up space.
13. A negatively charged ion.
16. A negatively charged particle that orbits an atom's nucleus.
17. Compounds that store energy and are part of cell membranes.
19. An atom with equal numbers of protons and electrons, so it has no charge.

1. The total number of protons and neutrons in an atom.
2. Any substance with a set of specific properties.
3. Large molecules essential for life, found in all living organisms. Examples include fats, proteins, and DNA.
5. A particle in an atom's nucleus with no charge.
6. Atoms of the same element with different numbers of neutrons.
7. A basic substance that cannot be broken down into simpler substances.
8. A positively charged particle in an atom's nucleus.
10. A substance made when two or more different elements bond together.
14. The number of protons in an atom.
15. Two or more atoms bonded together.
18. A positively charged ion.