1. Atomic Structure

2. Elements All elements are composed of only one type of atom. In these atoms are three subatomic particles: Protons Neutrons Electrons

3. Elements -Protons have a positive charge (+) -Neutrons have no charge (neutral) -Electrons Have a negative charge (-)

4. Most of the mass of an atom is found in the nucleus which contains the neutrons and protons.

6. Atomic number Atomic number tells you how many protons that elements has. If the number of protons changes, the element changes.

7. Atomic number Since the atom of an element is neutral, then the atomic number also tells you how many electrons you have. Atomic # = # of protons = # of electrons

8. Atomic Mass Atomic mass is the total number of protons and neutrons found in the nucleus of an atom. # of protons + #of neutrons = atomic mass

9. Neutrons To find out how many neutrons and element has: a)Round atomic mass to nearest whole number b)Subtract atomic number from atomic mass to get number of neutrons Atomic Mass – Atomic Number = # of neutrons

10. Example Na (sodium) Atomic mass is 22.989 Atomic mass rounded 23 Atomic number is 11 Atomic Mass – Atomic Number = # of neutrons 23-11= 12 Na has 12 neutrons.

11. Try these!!! Co (Cobalt) Atomic mass is 58.933 Atomic mass rounded 59 Atomic number 27 59-27= 32 Ag (Silver) Atomic mass is 107.868 Atomic mass rounded 108 Atomic number 47 108-47 = 61.

12. Bohr’s model Is a physical drawing that shows where all the subatomic particles are located in a particular atom of an element. The Bohr’s model is similar to our very own solar system.

13. Bohr’s Model Protons and neutron are always found in the nucleus of the atom of an element. Electrons are around the atom in an area called the electron cloud. In this electron cloud are orbitals where electrons move around the nucleus of the atom.

14. Bohr’s Model Each orbital can only hold a certain amount of electrons: 1 st orbital- 2 electrons 2 nd orbital- 8 electrons 3 rd orbital- 8 electrons 4 th orbital- 18 electrons

15. The elements found in a group have similar properties because they have the same number of valence electrons.

16. The horizontal rows on the periodic table are called a period. Periods tell you how many orbitals will be on your drawing. Ex. Na (sodium) is in Period 3, it will have 3 orbitals in its Bohr’s Model.

17. The vertical columns on the periodic table are called groups. Groups tell you how many valence electrons the element has. Ex. Na (sodium) is in Group 1 so it has 1 valence electron.

18. Valence electrons are the electrons that occupy the last orbital of an element. Orbitals are also called energy levels.

19. Boron (B) 5 p+ 6 n

20. Al 13 p+ 14 n

21. Lewis-Dot Structure The amount of dots you draw for a Lewis Structure (LS for short) is equal to the # of Valence Electrons in an Atom

22. Valence Electrons The # of Valence e- an atom has is dictated by the Group that the Element is in Groups are the Vertical Columns on the Periodic Table!!! It’s So Simple!!!!

23. Isotopes are atoms of a given element that have different numbers of neutrons and different mass numbers.

24. Ex. Oxygen-16; has 8 neutrons Oxygen-17; has 9 neutrons Oxygen-18; has 10 neutrons These are all still oxygen atoms.

25. Elements on the periodic table are classified as one of the following: Metals Nonmetals Metalloids