1. Upcoming Quiz  First 20 elements  Tin  Lead  You must know –the correct spelling of the name. –the correct symbol. 1

2. Objectives  PSc.2.1.4 – Interpret the data presented in the Bohr model diagrams and dot diagrams for atoms and ions of elements 1 through 18.

3. Modern View of the Atom  The atom has two regions and is 3-dimensional.  The nucleus is at the center and contains the protons and neutrons.

4.  The electron cloud is the region where you might find an electron and most of the volume of an atom. Modern View of the Atom

5. Subatomic Particles Electron Proton Neutron Name SymbolCharge Relative mass e-e- p+p+ n0n0 +1 0 1/2000 1 1 SymbolCharge Relative mass

6. Atomic Number  The atomic number of an element is the number of protons in the nucleus of an atom of that element.  The number of protons determines identity of an element, as well as many of its chemical and physical properties.

7. Mass Number  The sum of the protons and neutrons in the nucleus is the mass number of that particular atom.

8. Symbols  Elements can be represented by using the symbol of the element, the mass number and the atomic number. X Mass number Atomic number  The mass number is the atomic mass rounded to a whole number.

9. Problem  Determine the following for the fluorine atom depicted below. F 19 9 e) mass number d)atomic number c)number of electrons b)number of neutrons (9) (10) (9) (19) a)number of protons

10. Problem  Determine the following for the bromine atom depicted below. Br 80 35 e) mass number d)atomic number c)number of electrons b)number of neutrons (35) (45) (35) (80) a)number of protons

11. Problem Se 78 34 d) complete symbol c)number of electrons b)number of neutrons (34) (44) (34) a)number of protons  If an element has an atomic number of 34 and a mass number of 78 what is the

12. Problem Pa 231 91 d) complete symbol c)number of electrons b)mass number (91) (231) (91) a)atomic number  If an element has 91 protons and 140 neutrons what is the

13. Cations  A cation is a positive ion.  It is formed when an atom loses one or more electrons. Ca 2+

14. Anions  An anion is a negative ion.  It is formed when an atom gains one or more electrons. Cl 1-

15. Problem  Determine the following for the chlorine ion depicted below. Cl 1- 35 17 e) atomic number d)mass number c)number of protons b)number of electrons (18) (17) (35) (17) a)number of neutrons

16. Problem  Determine the following for the aluminum ion depicted below. Al 3+ 27 13 e) number of neutrons d)number of protons c)atomic number b)number of electrons (27) (10) (13) (14) a)mass number

17.  In 1910, J.J. Thomson discovered that neon consisted of atoms of two different masses. Isotopes

18.  Atoms of an element that are chemically alike but differ in mass are called isotopes of the element. Isotopes

19.  Consider the isotope of carbon that has a mass number of 14. The following are different ways to write symbols for this isotope. Isotopic Notation Carbon-14 C-14 14 C 6