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Warm-Up (10/1/14) 1.Write the charge and symbol for a proton, neutron, and electron. 2.If an atom has 37 protons, how many electrons must it have? Why?

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Presentation on theme: "Warm-Up (10/1/14) 1.Write the charge and symbol for a proton, neutron, and electron. 2.If an atom has 37 protons, how many electrons must it have? Why?"— Presentation transcript:

1 Warm-Up (10/1/14) 1.Write the charge and symbol for a proton, neutron, and electron. 2.If an atom has 37 protons, how many electrons must it have? Why? Pass forward your Rutherford Newspaper Article. Make sure the Rubric is stapled to the top.

2 Ch. 4 Notes (cont.) How Atoms Differ

3 I.Properties of Subatomic Particles ParticleSymbolLocationRelative Charge Relative mass Actual mass (g) Electron e - or In the space surrounding the nucleus 1- _1__ x Proton p+ or In the nucleus x Neutron n 0 or In the nucleus x

4 II. Atomic Number the number of protons in an atom Identifies element – each atom has unique # – # never changes Periodic table is arranged in increasing atomic #

5 III. Mass Number represents the total number of protons and neutrons in the nucleus # of neutrons = mass number – atomic number Rounded atomic mass number Ex: What is the mass number for boron? ANS: 11 (Round up to 11) Ex: How many neutrons does boron have? ANS: 6 neutrons (11-5 = 6)

6 IV. Isotopes Atoms of the same element but have a different # of neutrons Ex: 3 isotopes of carbon

7 All elements have isotopes (some 2, some 3, etc.) Some isotopes are naturally radioactive. Ex: Plutonium

8 V. Representing Isotopes In Ag-107, the 107 represents the mass number (neutrons + protons) OR:

9 Practice: 1. What is the mass number for Co-59? 2. What is the mass number for 59 7

10 VI. Atomic Mass The standard is the atomic mass unit (amu): defined as 1/12 of the mass of a carbon-12 atom the weighted average of the isotopes of that element. Formula: Atomic mass of an element = ( % abundance of Isotope #1 x mass of Isotope #1 ) + ( % abundance of Isotope #2 x mass of Isotope #2 ) + …

11 Practice 3 Silver has two naturally occurring isotopes. Ag-107 has an abundance of 51.82% and mass of amu. Ag-109 has a relative abundance of 48.18% and a mass of amu. Calculate the atomic mass of silver.

12 Practice 4 Rubidium is a soft, silvery-white metal that has two common isotopes, Rb and Rb. If the abundance of 85 Rb is 72.2% and the abundance of 87 Rb is 27.8%, what is the average atomic mass of rubidium?

13 Vocabulary to Know Atomic #: # of protons Mass #: # protons + # neutrons written 2 ways: Carbon-14 or C Isotopes-same # of protons, different # of neutrons Atomic mass-weighted average mass 14 6


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