Bell Work! Answer the three questions below… 1. What do the blue dots represent? 2. What charge do the white dots have? 3. Does this atom have a positive or negative charge? Protons Neutral Negative

Let’s Review… SPI 0807.9.1—Matter consists of atoms. Atoms are made up of protons, neutrons, and electrons. The protons (+) and neutrons (no charge) are found in the nucleus. The electrons (-) are on electron clouds outside the nucleus.

Atomic Model

Atomic Model

Atomic Model

Atomic Model

Atomic Model

How can you tell how many protons are in an atom of a given element? Atomic # vs. Mass # How can you tell how many protons are in an atom of a given element? Use the Periodic Table…look at the atomic #. Atomic Number—the number of protons in the nucleus of an atom…and it also tells you how many electrons it has All atoms of an element have the same atomic number. Example: Every hydrogen atom has an atomic # of 1. Every helium atoms has an atomic # of 2.

Atomic Number So…every Cobalt atom has 27 protons. And…if it has 27 protons, it also has 27 electrons.

Now you try… Using the periodic table, find the atomic number for the following elements: Nickel Calcium Lithium 28 20 3

Now, let’s determine how many neutrons are in each element. Mass Number—number of protons and neutrons in the nucleus of an atom (Atomic Mass) Round 58.6 to 59. then… 59 - 28 31 Mass #

Atomic Mass Number

Now you try… How many protons, neutrons, and electrons? 3 protons, 4 neutrons, 3 electrons Lithium 1 proton, 0 neutrons, 1 electron Hydrogen 4 protons, 5 neutrons, 4 electrons Beryllium Helium 2 protons, 2 neutrons, 2 electrons