Exam 2 Study Guide

Exam 2 Study Guide

1. What was wrong with Dalton’s atomic theory? What was wrong with Thompson’s atomic theory? What did Rutherford and Geiger’s experiment prove?

Dalton’s atomic theory was wrong because he stated that atoms are indivisible but atoms can be divided into protons, neutrons, and electrons. Dalton also said that atoms of the same element are similar in all respects but this is wrong because isotopes exist. Dalton also said that atoms of different elements are different in all respects. This is not true because there are some elements that have the same atomic mass as another element. Thompson’s atomic theory was also known as the plum pudding model, which proposed that protons and neutrons were scattered equally throughout an atom. Later it was discovered that protons and neutrons are found in the nucleus and electrons are not. Rutherford and Geiger’s experiment proved that an atom contains a nucleus where its positive charge and most if its mass is concentrated.

2. What is an atom? What are the three subatomic particles? Compare their charges and relative sizes. Where are these subatomic particles located in the atom?

An atom is the smallest particle of matter that represents a particular element. The three subatomic particles are protons, neutrons, and electrons. Protons have a positive charge, neutrons are neutral, and electrons have a negative charge. Protons and neutrons are similar in size with a relative mass of 1 and an electron is much smaller with a relative mass of 1/1836. Protons and neutrons are found in the nucleus and the electrons orbit the nucleus.

3. What are isotopes? **review atomic notation, calculation of protons, neutrons, and electrons in atoms, and calculation of weighted average atomic mass.

Isotopes are atoms of the same element that have different numbers of neutrons.

4. What is the radiant energy spectrum? What is the velocity or speed of each component? What part can humans see? What are cycle, wavelength, and...