2. CALIFORNIA Content Standards 8.3.a Students know the structure of the atom and know it is composed of protons, neutrons, and electrons. 8.7.b Students know each element has a specific number of protons in the nucleus (the atomic number) and each isotope of the element has a different but specific number of neutrons in the nucleus.

3. Tear one 3” × 3” paper in half Tear it in half again keep tearing in half until you can no longer tear the paper in half.

4. What gives a substance its properties? The number, type and arrangement of atoms.

5. What is an atom?The smallest part of an element. Matter is not something that contains atoms; Matter IS atoms. This is row upon row of atoms of the metallic element nickel. The picture was created using a scanning tunneling microscope. No other microscope can make images of things as small as atoms.

6. How small are atoms?Atoms are extremely small. Trillions of atoms would fit inside the period at the end of this sentence. If you magnified an atom 30 million times, it would be about the size of a grain of rice. If you magnified a soccer ball 30 million times, it would be the size of Earth!

7. Think about this Think about this: People are made of cells. Cells are made of atoms. If a small block of gold has about 1,077 sextillion atoms, then the number of atoms you are made of is too big to imagine.

8. What are atoms made of? A nucleus of protons and neutrons surrounded by a cloud of electrons.

9. Where is all of the mass of the atom found? The nucleus of the atom (protons and neutrons) accounts for 99.9% of the atom’s mass. nucleus electron cloud proton neutron

10. Protons Found in the nucleus Carry a positive electrical charge indicated by + symbol Has approx. the same mass as a neutron (1 amu)

12. Neutrons Found in the nucleus No electrical charge (neutral) Has same mass as proton, 1 u To find the # of neutrons, subtract the atomic # from the atomic mass

13. NEON Atomic Mass (rounded) – Atomic #= 20-10=10 neutrons

14. Electrons Energetic particles found in electron cloud around the nucleus (mostly empty space) Carry a negative charge (-) Close to zero mass # of protons = # of electrons (charges cancel out) outer electrons (valence) determine bonding power

15. 99.9% of the mass of the atom is found in the nucleus. An electron is about 2000 times smaller than either a proton or a neutron. The diameter of the nucleus is 1/1000 of the diameter of the whole atom. The size of the electron cloud determines the size of the atom. Most of the electron cloud is empty space. Some Number Facts For you…

17. What does the atomic weight/mass mean on the periodic table? The sum of protons and neutrons in an atom. 99.9% of the mass of the atom is found in the nucleus. Represented by symbol

18. What is the atomic #? Every atom has a unique atomic number, or number of protons, in its nucleus. Every atom of a particular element contains the same number of protons.

19. How small are atoms? TED talks https://www.ted.com/talks/just_how_small_is _an_atom Atom Songs: Mr. Parr https://www.youtube.com/watch?v=_lNF3_3 0lUE

20. The number of protons is called atomic number, and it is constant for all atoms of the same element. The number of electrons and neutrons may vary within atoms of the same element. (A different number of electrons makes up positive/negative ions; a different number of neutrons makes up different isotopes of the same element.) This is a high school standard and should not be discussed in middle school.