Chapter 2: Atoms

Question 1

what did Dalton believe

Answer 1

that atoms were made of smaller sub atomic particles

Question 2

what did Thomson discover

Answer 2

that atoms had positively and negatively charged particles that cancelled out to become neutral

+ plum pudding model that said that the electrons were spread out in a field

Question 3

what did Rutherford discover

Answer 3

by firing particles at a gold foil he discovered that they were mostly empty space with most of their mass concentrated in the nucleus

Question 4

what did Chadwick discover

Answer 4

neutrons

Question 5

what is electrostatic attraction

Answer 5

the force that attracts oppositely charged particles together

this holds atoms together as electrons are attracted to the positively charged nucleus

Question 6

what is the difference between isotopes and atoms

Answer 6

isotopes have the same number of protons but different amounts of neutrons

resulting in a different mass number

Question 7

what are the 4 ideas of the bohr model

Answer 7

fixed circular orbit

further orbit = higher energy

cannot exist between levels

each shell corresponds to an energy level

Question 8

what is an isotope

Answer 8

same number of protons different number of neutrons leading to radioactivity

Question 9

the relative atomic mass of rubidium is 85.47. The relative atomic mass of two isotopes, 85-Rb and 87-Rb are 84.95 and 86.94. calculate the relative abundance of each isotope

Answer 9

lighter isotope abundance = x
therefore heavier isotope = 100-x
85-Rb = x
87-Rb = 100-x

85. 47 = 84.95x + 86.94(100-x)/100
86. 47 = 84.95*x + 8694 - 86.94x/100
    - 147 = -1.99x

x=147/1.99

x=73.87%

85-Rb=73.87%

therefore 87-Rb = 26.13