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 • 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. (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

Ch. 3: “Atoms & the Periodic Table”