Presentation is loading. Please wait.

Presentation is loading. Please wait.

How Atoms Differ October 2, 2014. Reading an Element  A – Atomic Number: the number of protons in an atom (this identifies the element)  B – Average.

Similar presentations


Presentation on theme: "How Atoms Differ October 2, 2014. Reading an Element  A – Atomic Number: the number of protons in an atom (this identifies the element)  B – Average."— Presentation transcript:

1 How Atoms Differ October 2, 2014

2 Reading an Element  A – Atomic Number: the number of protons in an atom (this identifies the element)  B – Average Atomic Mass  C – Chemical Symbol  D – Chemical Name

3 Atomic Number - Z  All atoms are neutral, the charges of the protons and electrons must cancel each other out  Atomic Number = number of protons = number of electrons Fill in the table below. Element Atomic Number ProtonsElectrons Pb

4 Isotopes  Isotopes are atoms with the same number of protons but different number of neutrons.  The atomic number stays the same  Mass will change, since neutrons have a relative mass of 1

5 Isotope Notation  Mass Number – the sum of the atomic number(or number of protons) and neutrons in the nucleus  These are both saying that the element is carbon, it has a mass number of 14, atomic number of 6  So 6 protons, 6 electrons, and 8 neutrons Carbon -14

6 Fill in the table below ElementMass #Atomic # Protons & Electrons Neutrons Isotope Symbol Neon2210 Calcium4620 Oxygen178 Iron5726 Zinc6430 Mercury20480

7 Atomic Mass  An Elements mass is made up of protons (1 amu) and neutrons (1 amu)  However an elements mass is usually never a whole number.  Atomic Mass of an element is the weighted average mass of the isotopes of that element

8 Calculating Atomic Mass  Chlorine – 35 has a mass of amu, a percent abundance of 75.78%  Chlorine – 37 has a mass of amu, a percent abundance of 24.22%  Calculate the mass contribution of each isotope  Chlorine – 35: ( amu x 75.78%) = amu  Chlorine – 37: ( amu x 24.22%) = amu  Now add the isotopes mass contribution together to get your weighted average atomic mass  ( amu amu) = amu  The weighted average atomic mass should be the same or very close to what is on the periodic table.

9 Isotope Practice  Boron has two naturally occurring isotopes: boron – 10 (abundance = 19.8%, mass = amu) and boron – 11 (abundance = 80.2%, mass = amu). Calculate the mass of boron.  Identify the unknown element X, based on the information given in the table.  Nitrogen has two naturally occurring isotopes, N -14 and N- 15. Its atomic mass is amu. Which isotope is more abundant? Explain. IsotopeMass (amu)Percent Abundance X – % X %


Download ppt "How Atoms Differ October 2, 2014. Reading an Element  A – Atomic Number: the number of protons in an atom (this identifies the element)  B – Average."

Similar presentations


Ads by Google