Chapter 2: Atoms, Molecules, and Ions

Question 1

What are the four parts of John Dalton’s Atomic Theory?

Answer 1

1. All elements are composed of atoms.
2. All atoms of an element are identical, but atoms of different elements are different.
3. Atoms of one element cannot be changed into atoms of a different element by chemical reactions; atoms are not created nor destroyed in chemical reactions
4. Compounds form when atoms of more than one element combine; a given compound always has the same relative number of kind of atoms

Question 2

What part of Dalton’s Theory may no longer be true?

Answer 2

That atoms are not created or destroyed in chemical reactions. The idea of radioactivity.

Question 3

Dalton’s Theory vs. Laws

Answer 3

1. Atoms of an element are not changed into different types of atoms by chemical reactions. —> Law of Conservation of Matter
2. A compound always has the same number and kind of atoms. —> Law of Constant Composition
3. When two elements form different compounds, the mass ratio of the elements in one compound is related to the mass ratio in the other by a small whole number —> Dalton’s Law of Multiple Proportions

Question 4

What are atoms composed of?

Answer 4

Subatomic particles. Protons (positive) and electrons (negative)

Question 5

What is the law of attraction?

Answer 5

Particles with the same charge repel each other, and particles with opposite charges attract one another

Question 6

How were electrons discovered?

Answer 6

In a cathode ray tube. A stream of cathode rays (electrons) were generated at the cathode (negative) end, and traveled to the anode (positive) end.

Question 7

What happened when a magnet was used in the cathode ray tube?

Answer 7

The rays (electrons) passed through the hole and were deflected by magnetic and electric fields.

Question 8

What are the three types of radiation?

Answer 8

Alpha particles, beta particles, gamma rays

Question 9

What was Rutherford’s experiment?

Answer 9

alpha and beta particles are bent by an electrical field in opposite directions; gamma rays are unaffected

Question 10

What are beta particles?

Answer 10

• high speed electrons
• attracted to the positively charged plate
• charge of 1^-

Question 11

What are alpha particles?

Answer 11

• higher mass than beta particles
• attracted to the negatively charged plate
• Positively charged core of a He atom with a charge of 2^+

Question 12

What are gamma rays?

Answer 12

• high energy
• similar to x-rays
• not particles so no charge

Question 13

What do Li, Na, and K all have in common being in Group 1 on the periodic table?

Answer 13

all soft, very reactive metals

Question 14

What do He, Ne, and Ar have in common all being in Group 18?

Answer 14

very non-reactive gases