Understanding Matter

Atomic Theory

100

Who discovered the densely packed nucleus?

Rutherford

200

Who created the modern model of the atom?

Bohr

300

Who conducted the cathode ray experiment?

Thomson

400

What was Democritus' theory?

All matter is composed of tiny indivisible particles.

The Periodic Table

100

Neon is in which group?

Noble gases

200

The ____ are the most reactive group.

Halogens

300

Elements in the same group have the same number of ______

valence electrons

400

How many valence electrons does Na have?

1

Isotopes

100

How many neutrons are in ¹⁶⁷₇₈Ir?

89

200

What is the mass number of an element with 26 protons, 20 neutrons, and 46 electrons?

46

300

Boron has two naturally occuring isotopes ¹⁰B and ¹¹B. Based on the average atomic mass, which is the most abundant?

¹¹B

400

Calculate the average atomic mass of copper given the following data:

Cu-65 (30.8%)
Cu-63 (69.2%)

63.62

Nuclear Decay

100

²⁰²₈₈Ra --> ¹⁹⁸₈₆Rn + _____

⁴₂He

200

⁴⁵₂₀Ca --> ____ + ⁰_-1e

⁴⁶₂₁Sc

300

____ --> ⁹⁸₄₆Pd + ⁰₊₁e

⁹⁸₄₇Ag

400

Which type of decay does not change the identity of the element?

Gamma

Half Life Calculation

100

Cesium-137 has a half life of 30 years. If a 1. g sample is left to decay for 90 years, how many grams of Cs-137 would remain?

0.125 g

200

A sample has a half life of 29 hours. How many half lives will pass in 58 hours?

2

300

An isotope has a half life of 2 years. How long would it take for a 4.0 g sample to decay down to 0.50 g?

6 years

400

How long would it take a 10 mg sample to decay down the 1.25 mg if the half life is 25 min?

75 min