The Atomic Structure

2. ~ the mass of a single atom
4. ~ a subatomic particle of about the same mass as a proton but without an electric charge, present in all atomic nuclei except those of ordinary hydrogen.
5. ~ a group of atoms bonded together, representing the smallest fundamental unit of a chemical compound that can take part in a chemical reaction.
8. ~ closely packed together and contain the least amount of kinetic energy.
11. ~ Danish physicist who made foundational contributions to understanding atomic structure and quantum theory, for which he received the Nobel Prize in Physics in 1922.
12. ~ table of chemical elements
15. ~ a Russian chemist and inventor. He is best remembered for formulating the Periodic Law and creating a farsighted version of the periodic table of elements.
19. ~ a part or aspect of something abstract, especially one that is essential or characteristic.

1. ~ The weight of a substance
3. ~ the number of protons found in the nucleus of every atom of that element.
6. ~ no definite shape (takes the shape of its container)
7. ~ two or more atoms chemically joined together
9. ~ subatomic particle with a positive electric charge
10. ~ atoms move freely
13. ~ the basic unit of a chemical element.
14. ~ its mass per unit volume
16. ~ the small, dense region consisting of protons and neutrons at the center of an atom
17. ~ subatomic particle with a negative electric charge
18. ~ the area around an atom's nucleus where electrons are most likely to be found