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Chapter 2,: Atoms and Elements; Ions, Molecules and Compounds
The model of the atom we use today is called the ______________ __________. It is
made up of ______________________ particles.
Electrons: Michael Faraday (1791 – 1867)
Sir J.J. Thomson (1856 – 1940)
Robert Millikan (1868 – 1953)
Electron mass:
Electron charge:
Protons: Ernest Rutherford (1871 – 1937)
Proton mass:
Proton charge:
Neutrons: James Chadwick (1891 – 1974)
Neutron mass:
Neutron charge:
How are these subatomic particles put together? Ernest Rutherford determined that all
_____________ charge and most of the _________ is concentrated in a __________
_________ volume in the _____________ of the atom; the ________________ occupy
the rest of the space. The __________________ is the center which contains
_____________ and _______________. For the atom to have a _______________
charge (__),_________________________
Atomic Composition
Atomic Mass Unit: The amu has been defined as
1 amu =
Atomic Number (Z):
See the ___________ of the square for each element in the periodic table.
Mass Number:
The actual mass is not the same as the mass number (except ______).
Isotopes: Atoms of the _________ atomic number but _______________ mass
number; they contain different numbers of ________________.
Ex. H
# protons
# neutrons
Tritium is an example of a _________________ isotope:
It undergoes ________________:
β particle:
α particle:
γ ray
X ray:
# electrons
Atomic Mass: The _______________ mass of atoms in a
naturally occurring sample of an element which contains a mixture
of __________________.
Example. What is the atomic mass of Cl given this information:
% in naturally occurring sample
mass
35
Cl
Cl
37
The Periodic Table
Dmitri Mendeleev (1834 – 1907):
Elements having similar __________________ and __________________ properties
lie in vertical columns called _________________.
The atomic mass of sulfur is:
This is the mass of ____________ of sulfur atoms, in grams.
So, 1 amu = 1 g/mol.
We call the mass of 1 mole of substance its ______________ ___________.
A mole is
We call this
How many moles of copper are there in 6.50 g of copper?
How many atoms are there in 3.559 x 10-6 mol of argon?
How many atoms are there in 30.1 g of magnesium?
What mass of zinc contains the same number of atoms as 90.15 g of helium?
Homework: Chap 2 #15, 17, 19, 21, 27, 29, 31, 39, 41, 47, 49, 51, 53, 57, 59, 61, 67, 76