1. The Atom and Its Parts

2. Objectives  Estimate the size of an atom  List the parts of the atom, their location and their charge.  Learn the elements that are important for living things to survive (CHNOPS)  Learn how to model CHNOPS (in Class)

3. Think! Think!! Think!!  What do you know about the atom?

4. Think! Think!! Think!!!  You probably remembered that atoms are very tiny. Also, everything in the universe is made of atoms, including everything that is alive.  Living things are made of cells, and cells are made of atoms. There are about 100,000,000,000,000 (100 trillion) cells in your body. Each one of those cells is made up of 100,000, 000, 000 (100 trillion) atoms!

5. The Atom  Even though atoms are tiny, they are made of even tinier parts.  The protons  The neutrons  The electrons  Protons and neutrons are located in the nucleus.

6. The Nucleus  The nucleus is the center of the atom. The same word is used to refer to the center of a cell.  In the nucleus are the protons and neutrons.

7. The Nucleus  The proton is a particle in the nucleus with a positive charge. Protons repel, or move away from each other. “Proton” and “Positive” both start with “p.”  Atoms can have anywhere from 1 to 118 protons.

8. The Nucleus  The neutron is the particle in the nucleus that is neutral, or has no charge. I call them the “glue of the nucleus.” Without them, the protons would repel each and fly apart!  An atom can have anywhere from 0 to 146 neutrons.

9. The Electron  The electron is tiniest of all the parts of the atom.  The electron has a negative charge.  They move at very high speeds around the nucleus in paths called energy levels. Energy levels resemble orbits.  An atom can have anywhere from 1 to 118 electrons.

10. Energy Levels  The first energy level is located closest to the nucleus. It can hold two electrons.  The second energy level can hold eight electrons.  The third energy level can hold eighteen electrons.  There are more energy levels but we will only be concerned with elements that have electrons in the first three energy levels.

11. Elements  There are only 118 different kinds of atoms.  An element is matter is which all the atoms are the same  Are you an element?  The elements are organized into the periodic table.  Some common elements are carbon, hydrogen, aluminum, gold, and oxygen.

12. Ions  When the number of protons is equal to the number of electrons in an atom, we say the atom is neutral.  Sometimes, atoms can gain or lose an electron. Then the number of electrons is not equal to the number of protons. The atom is then called an ion.

13. Isotope  Sometimes, elements can have many different forms. The number of electrons and protons are the same but the number of neutrons is different. That form of an element is called an isotope.  For example, hydrogen has three forms or isotopes called protium, deuterium and tritium. The only difference between them is the number of neutrons.

14. CHNOPS  The essential elements which make up living things are easy to remember. C = carbon H = hydrogen N = nitrogen O = oxygen P = phosphorus S = sulfur

15. The Atom  In class, we will practice making models of atoms.