1. Warm-Up? Q). What information do you think you can get about elements reading the periodic table?.

2. Elements are a substance that can not be separated or broken down into simpler substances by chemical means. Each element contains only one set of particles. These particles are called atoms. Elements

3. Example: the element copper is made of only copper atoms

4. Atom: the smallest unit of matter that retains the identity of the substance Atoms

5. Atomic Structure Atoms are composed of 2 regions: – Nucleus: the center of the atom that contains the mass of the atom – Electron cloud: region that surrounds the nucleus that contains most of the space in the atom

7. What’s in the Nucleus? The nucleus contains 2 of the 3 subatomic particles and most of the mass of an atom: – Protons: positively charged subatomic particles – Neutrons: neutrally charged (no charge) subatomic particles

8. Electrons The 3 rd subatomic particle resides outside of the nucleus in the electron cloud – Electron: the subatomic particle with a negative charge and relatively no mass

9. How do these particles interact? Protons and neutrons live compacted in the tiny positively charged nucleus accounting for most of the mass of the atom The negatively charged electrons are small and have a relatively small mass but occupy a large volume of space outside the nucleus

11. The atomic number is the number located on top and the atomic mass/weight is the decimal number located on the bottom. - As in this example for krypton: Using the Periodic Table of Elements to find Out the Number of Protons, Neutrons, and Electrons are in Each Atom

12. The atomic number is the number of protons in an atom of an element. In our example, krypton's atomic number is 36. This tells us that an atom of krypton has 36 protons in its nucleus. Finding the Number of Protons

13. The interesting thing here is that every atom of krypton contains 36 protons. If an atom doesn't have 36 protons, it can't be an atom of krypton. Adding or removing protons from the nucleus of an atom creates a different element. For example, removing one proton from an atom of krypton creates an atom of bromine. Protons

14. By definition, atoms have no overall electrical charge. That means that there must be a balance between the positively charged protons and the negatively charged electrons. Atoms must have equal numbers of protons and electrons. # Protons = # of Electrons The Number of Electrons is...

15. An atom can gain or lose electrons, becoming what is known as an ion. Don’t worry, we will get to that later! Losing Electrons

16. The atomic mass is basically a measurement of the total number of particles in an atom's nucleus. Nucleus/Atomic mass= (Number of Protons) + (Number of Neutrons) The Number of Neutrons is...

17. So then….to find the number of neutrons, all you need to do is … 1.Round the atomic mass to the nearest whole number 2.Subtract the number of protons (Atomic Number) from the atomic mass. The Number of Neutrons is...

18. In our example, krypton's atomic mass is 84. * 83.80, rounds up to 84. 1. Round the atomic mass to the nearest whole number

19. Then all we have to do is plug in the numbers… 84 = 36 + (Number of Neutrons) 84-36 = 48 Krypton has 48 neutrons The Number of Neutrons is...

20. For any element: Atomic Number = Number of Protons Number of Protons = Number of Electrons Number of Neutrons = Atomic Mass (rounded) - Atomic Number In Summary...