Transcript Atoms: The Building Blocks of Matter

Chapter 3
Atoms:
The Building Blocks of Matter
The Atom: From Philosophical Idea to
Scientific Theory
The Structure of the Atom
Weighing and Counting Atoms
Dalton’s Atomic Theory
All matter composed of atoms
Atoms of a given element are
identical in size, mass and other
properties. Atoms of different
elements are different.
Atoms can’t be created or destroyed.
Atoms combine in whole-number
ratios in chemical compounds.
In chemical reactions, atoms are
combined, separated, and rearranged.
Law of Multiple Proportions
If two or more different compounds are
composed of the same two elements, the
masses of the second element combined with
a certain mass of the first element can be
expressed as ratios of small whole numbers.
The Structure of the Atom
Atomic Structure
The Atom
identity and arrangement of smaller particles in atoms
two main regions
Proton
located in the nucleus
positive charge
discovered by Rutherford
Neutron
located in the nucleus
no charge
neutrons were used to split the first atom
Electron
located outside the nucleus in the electron cloud
negative charge
Millikan discovered the mass and charge
The Isotopes of Hydrogen
Protium
1 proton
0 neutrons
1 electron
Deuterium
1 proton
1 neutron
1 electron
Tritium
1 proton
2 neutrons
1 electron
Atomic Number: (Z)
The number of protons
in the nucleus of each
atom of that element
Mass Number: total
number of protons and
neutrons in the nucleus
of an isotope
Nuclide: is a general term for any isotope of any element
Isotopes: atoms of the same element with different masses
Average Atomic Mass
Calculating Average Atomic Mass
Average Atomic Mass:
weighted average of the atomic
masses of the naturally occurring
isotopes of an element
Isotope 1
Mass
X
relative abundance
Isotope 2
Mass
X
relative abundance
Isotope 3
Mass
X
relative abundance
Steps for Solving Quantitative Problems
Read the problem carefully at least twice. Note any
important descriptive terms that add meaning to the
problem.
Your plan for solving a problem should show how the
information given in the problem is used to find a
solution.
Substitute the data and conversion factors into your plan
from Step 2.
Always look back at your answer to determine if it is
reasonable.
Divide by 6.02x1023
Divide by molar mass
Mass
Multiply by molar mass
Mole
Particle
Multiply by 6.02x1023
The End