# Ch. 3: “Atoms & the Periodic Table”

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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 neutron: 0, 1.67 x 10-27kg, in the nucleus electron: -1, 9.11 x 10-31kg, outside the nucleus

4. Predict how many valence e-’s a nitrogen atom has
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
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
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.

In Bohr’s model, e-’s travel in fixed paths.
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