2.  Atom – the smallest particle of an element that retains the properties of that element.  When we say “small,” we mean “SMALL!”  A typical copper penny contains 29,000,000 000,000,000,000,000 atoms (2.9 x 10 22 atoms)  Current world population is (as of 9/24) 7,360,000,000 people (7.36 x 10 9 people)

3.  There are two main parts in each atom Nucleus ◦ Protons ◦ Neutrons Electron Cloud ◦ Electrons ◦ Lots and lots of empty space

4.  Protons are located in the nucleus  These are positively charged subatomic particles.  Carries a single unit of positive charge (+1)  These are 1840 times more massive than an electron.  Mass is 1.673 x 10 -27 kg.

5.  Neutrons are located in the nucleus  These are subatomic particles with no charge  Their mass is about the same as that of the proton  Mass is 1.675 x 10 -27 kg.

6.  Electrons are located in the electron cloud.  Carries a single unit of negative charge (-1)  The mass of an electron is about 1/1840 th that of a proton or neutron  Mass is 9.1 x 10 -31 kg.

7. ParticleSymbolRelative Charge AMUActual Mass (kg) Proton p+p+ 1+11.673 x 10 -27 Neutron n0n0 011.675 x 10 -27 Electron e-e- 1-1/18409.1 x 10 -28

8. There are in differences among the number of subatomic particles.

9.  The atomic number of an element is the number of protons in the nucleus of the atom of that element.  Atoms are neutral, so therefore, the number of protons must equal the number of electrons in an atom.  Where can I find this?  Look on the Periodic Table

11.  Locate the element on the Periodic Table  The atomic number = the number of protons in every atom of that element Every atom of Cobalt contains 27 protons

12.  The mass number is the sum of the number of protons and neutrons in the nucleus of an atom.  The units for mass number are “AMU” which stands for atomic mass unit.  One AMU is defined as the 1/12 th the mass of a carbon atom that contains 6 protons and 6 neutrons.  The vast majority of the mass of an atom is concentrated in the nucleus (protons and neutrons)

13.  What is the mass number of an atom that has 8 protons and 8 neutrons? And, what is the identity of this element?  8 protons + 8 neutrons = 16 AMU  The element is oxygen

14.  Contrary to Dalton’s ideas, all atoms of the same element are NOT IDENTICAL.  Nuclei of atoms of a given element must contain the same number of protons, but the number of neutrons may vary.  Isotopes are atoms that have the same number of protons, but different numbers of neutrons.  This means that isotopes of the same element have different mass numbers

15.  Isotopes are written as the chemical symbol with two additional numbers to the left side of it. 11 5 B  Mass number is a superscript  Atomic number is a subscript.  This is called a “nuclear symbol” for the particular element

16.  Hyphen notation is a shorthand for the nuclear symbol. Lithium–7 Li-7  The name of the element is spelled out or written as symbol  There is a dash and then the mass number is listed

17.  Atomic mass is the weighted average of the masses of the isotopes of that element. The atomic mass of Cobalt is 58.93320 g/mol. One mole of Co atoms will have a mass of 58.93320 g

18.  The atomic mass of Cobalt is 58.93320 g/mol.  When atomic mass is rounded to the nearest whole number, you can determine the mass number of the most common isotope.  For Co, 58.93320 g rounds to a mass number of 59. This means that the most common isotope of Co is Co-59, which has 27 protons and 32 neutrons.

19. If Copper has two isotopes, Cu-63 and Cu-65, and the atomic mass is 63.546, which of the two isotopes is more common (abundant)? Since 63.546 is closer to 63 then 65, there must be a greater abundance of Cu-63 then Cu-65.