2.5 - 2.7 The Structure
of The Atom, Subatomic
Particles, & The
Periodic Table
The Structure of the Atom
• Explain Ernest Rutherford’s experiment:
– 1.) What was it called?
– 2.) Describe it?
– 3.) What did Rutherford discovery?
1.) The gold foil experiment.
2.) Used a radioactive source that emitted alpha
particles at a piece of gold foil. Most went through,
but some bounced back at extreme angles.
3.) The atom is made up of mostly empty space, but has
a small dense positively charged nucleus.
Nuclear Theory
Where is most of the mass of the atom, and why what
makes up this mass?
– The nucleus, which is made up of protons and neutrons.
What subatomic particle orbits this mass and where
are they found?
– Electrons, which are found in orbitals.
When an atom is electrically neutral, the atom has as
many ? as ?
– Protons and electrons
Properties of Subatomic Particles
Particle
Mass (amu)
Charge (relative)
Symbol
Particle
Mass (amu)
Charge (relative)
Symbol
Proton
1
+1
p+
Neutron
1
0
n0
Electron
0
-1
e-
Proton
Neutron
Electron
Identifying an Element
When looking at the periodic table, which number identifies the
element? Which subatomic particle does this number
represent? What is the symbol of this number?
Atomic number (number of protons), indicated by the symbol Z
A unique one, two or three letter abbreviation of an element is
called its…? How is this abbreviation written?
Chemical symbol written so that the first letter is always
capitalized, and letters that follow are lowercase.
Isotopes
What is an isotope? Give an example.
An isotope is an atom with the same number of protons,
but a different number of electrons.C-12, C-13, and C-14,
each have 6 protons, but a different # of neutrons.
How many neutrons does C-14 have, and what does the
14 in C-14 represent?
8 neutrons. The 14 is that isotopes mass number (protons
+ neutrons). The mass number is symbolized by an A
Ions
What is an ion? Give an example.
An atom that loses or gains electrons. Ca2+ is an example of an
ion. What must have happened to calcium for it to have a
charge of 2+? Is Ca2+ an anion or cation?
Calcium lost two electrons, and became a cation. Is the size of
the calcium ion larger or smaller than the calcium atom? Why?
The calcium ion is smaller than the calcium atom, because the
loss of two electrons results in less e- to e- repulsion, bringing
the remaining electrons closer to the strong positively charged
nucleus.
Let’s Locate The Following on the
Periodic Table
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Metals
Non-metals
Metalloids
Groups (or Families)
Periods
Main Group Elements
Transition Elements (Transition Metals)
Halogens
Alkaline Earth Metals
Alkali Metals
Noble Gases
What is periodic law?
Chapter 2 pg. 80 #’s 52, 54, 58, 63, 68, 70
Read: 2.8 – 2.9 pgs. 66-75