2. Sub atomic Particles: particles inside an atom  Proton = p +  Electron = e -  Neutron = n 0 Protons & Neutrons have the most mass and are located in the center of the atom – nucleus. Electrons are have such a small mass – they are considered almost massless

3. Atomic # is the number at the top of each block on the periodic table  Atomic # = #p  Neutral Atom #p = #e- 1 H 1.00784

4.  mass # = protons + neutrons  Number of protons and neutrons in the nucleus  always a whole number  NOT on the Periodic Table! © Addison-Wesley Publishing Company, Inc.

5.  Hyphen Notation: element name – mass #  Nuclear Symbol: Mass # atomic # symbol Mass # Atomic #  Nuclear symbol:  Hyphen notation: carbon-12

6.  Chlorine-37 › atomic #: › mass #: › # of protons: › # of electrons: › # of neutrons: 17 37 17 20

7. Carbon – 12 Atomic # Mass# #P #E #N What is the same? What is different? Carbon – 14 Atomic # Mass# #P #E #N

8.  Atoms of the same element with different mass numbers.(because of different #neutrons) © Addison-Wesley Publishing Company, Inc.

9.  Boron – 10 Boron – 11 Boron – 13  Which of these has more neutrons?

10.  There are billions and billions of atoms in any element on the periodic table.  All the atoms in element have isotopes: same atom but with a different mass.  How do we know what the mass of all those atoms will be?

11. 8 8 Average Atomic Mass 12 14 12 14 12

12.  Average Atomic mass: the average mass of ALL the isotopes of that element.  This number is located on the bottom of each block on the periodic table  Not a whole number  Different from the Mass #

13.  Mass #: is the mass of a single atom  Similar to a grade on an assignment in class.  Average Atomic Mass: is the average mass of billions of atoms  Similar to your average at the end of the year – an average of all your assignment grades

14. 8 8 Average Atomic Mass 12 14 12 14 12

16.  Models: reasonable representation of a very large or a very small object.  Atoms are very tiny and we can not physically see the parts of an atom – so a model (drawing) is used to represent the atom.  Atomic structure is an important property of an atom and it must be represented correctly.

17.  Proton & Neutrons are in the nucleus,  Electrons move around the nucleus – but they are in specific locations around the nucleus.

18.  Electrons are very tiny, have almost no mass, and move very fast.  The location of an electron is hard to identify because it moves so fast – so electrons are modeled by an electron cloud or ring around the nucleus.  When drawing models of atoms – it is important that the electrons are drawn in the correct ring!

19.  The most important electrons in an atom are the valence electrons.  Valence electrons are the electrons in the last ring. › Determine the ion charge › Determine the chemical properties › Determine the type of bonding

20.  Drawing of an atom that includes the 3 sub atomic particles. (drawing of the PEN table)  Protons and neutrons in nucleus  Electrons in rings around the nucleus › 2 electrons in 1 st ring › 8 electrons in 2 nd ring Boron – 11 Atomic # Mass# #P #E #N # Valence electrons

21.  Draw a Bohr Model for the following: Beryllium – 7Magnesium – 24PE N # Valence electrons