Transcript Ch. 3: “Atoms & the Periodic Table”

Ch. 3: “Atoms & the
Periodic Table”
Section 3.1 Review: “Atomic
Structure”
1. Summarize the main ideas of
Dalton’s atomic theory.
Elements are made of tiny, unique
particles called atoms.
 Atoms cannot be divided.
 Atoms of the same element are identical.
 Atoms of different elements can join to
form molecules.

2. Explain why Dalton’s theory was more
successful than Democritus’s theory.

Evidence existed to support Dalton’s
theory.
3. List the charge, mass, & location of each
of the 3 subatomic particles found within
atoms.
proton: +1, 1.67 x 10-27kg, in the nucleus
-27
 neutron: 0, 1.67 x 10 kg, in the nucleus
-31
 electron: -1, 9.11 x 10 kg, outside the
nucleus

4. Predict how many valence e-’s a nitrogen
atom has. (Nitrogen has a total of 7 e-’s, 2 of
which fill the lowest energy level.)

5 valence e-’s
5. Explain why oxygen atoms are neutral.
(Oxygen has 8 positively charged p+’s.)

Oxygen has 8 negatively charged e-’s to
balance out the charge of the 8 positively
charged p+’s.
6. Compare an atom’s structure to a ladder. What parts of
the ladder correspond to the energy levels of the atom?
Identify one way a real ladder is not a good model for the
atom.
The nucleus is underground. Each rung of
the ladder represents an energy level.
Electrons can only be on the rungs, not
between rungs.
 A ladder is not a good model for an atom
because all of the rungs are the same
distance apart.

7. Explain how the path of an e- differs in Bohr’s
model & in the modern model of the atom.
In Bohr’s model, e-’s travel in fixed paths.
 In the modern model, e ’s exist in certain
regions & can have only certain energies.

8. Critical Thinking
What do you think the majority of an atom is
made of?
 empty space
What part of the atom caused the particles
to bounce back?
 the nucleus