Advertisement Upgrade to remove ads

Model

A schematic description of a system that accounts for its known properties.

Nucleus

The center of an atom, containing the protons and neutrons.

Atomic number

The number of protons in an atom.

Mass number.

The sum of the numbers of neutrons and protons in the nucleus of an atom.

Isotopes

Atoms with the same number of protons but different numbers of neutrons.

Element

A collection of atoms that all have the same number of protons.

Radioactive isotope

An atom with a nucleus that is not stable.

Half-life

The time it takes for half of the original sample of a radioactive isotope to decay.

Order the three constituent parts of the atom in terms of their mass, from the least massive to the most massive.

Electron, proton, and neutron.

What force keeps the protons and neutrons in the nucleus? What causes this force?

The nuclear force. This force is caused by the exchange of pions between protons and/or neutrons.

What force keeps the electrons orbiting around the nucleus?

Electromagnetic force.

What is an atom mostly made of?

Empty space.

An atom has an atomic number of 34. How many protons and electrons does it have? What is its symbol?

34. 34Se.

List the number of protons, electrons, and neutrons for each of the following atoms:
A. Neon-20 (neon's chemical symbol is "Ne")
B. 56Fe
C. 139La
D. 24Mg

A. 10. B. 30. C. 82. D.12.

Two atoms are isotopes. The first has 18 protons and 20 neutrons. The second has 22 neutrons. How many protons does the second atom have?

18.

Which of the following atoms are isotopes?
112Cd, 112Sn, 120Xe, 124Sn, 40Ar, 120Sn.

112Sn, 124Sn, 120Sn.

Draw what the Bohr model says an 16O atom would look like.

Finger drawn.

Draw what the Bohr model says a 25Mg atom would look like.

Finger drawn.

What is the largest Bohr orbit in a uranium atom (the symbol for uranium is "U"), and how many electrons are in it?

5, 32.

Why is the strong nuclear force such a short range-force?

Since pions have a very short lifetime, the strong nuclear force can only act over very tiny distances.

Determine the daughter products produced in the beta decay of the two radioactive isotopes shown below: a. 98Te b. 125I

a. 98Ru. b. 125Xe.

Determine the daughter products produced in the alpha decay of two radioactive isotopes shown below: a. 212Bi b. 224Ra

A. 208Ti B. 220Rn.

A radioactive isotope goes through radioactive decay, but the isotope's number of protons and neutrons does not change. What kind of radioactive decay occurred?

Gamma decay.

The half-life of the radioactive decay of 226Ra is 1,600 years. If a sample of 226Ra originally had a mass of 10 grams, how many grams of 226Ra would be left after 3,200 years?

2.5 grams.

The half-life of the man-made isotope 11C is 20 minutes. If a scientist makes 1 gram of 11C, how much will be left in one hour?

0.125 grams

Why is radioactive dating unreliable in most situations?

Radioactive dating is usually unreliable because assumptions must be made as to the original condition of the object. These assumptions are usually incorrect.

List the three types of radioactive particles discussed in this module in the order of their ability to travel through matter. Start with the particles that cannot pass through much matter before stopping, and end with the one that can pass through the most matter before stopping.

Alpha particles, beta particles, and gamma particles.

Please allow access to your computer’s microphone to use Voice Recording.

Having trouble? Click here for help.

We can’t access your microphone!

Click the icon above to update your browser permissions above and try again

Example:

Reload the page to try again!

Reload

Press Cmd-0 to reset your zoom

Press Ctrl-0 to reset your zoom

It looks like your browser might be zoomed in or out. Your browser needs to be zoomed to a normal size to record audio.

Please upgrade Flash or install Chrome
to use Voice Recording.

For more help, see our troubleshooting page.

Your microphone is muted

For help fixing this issue, see this FAQ.

Star this term

You can study starred terms together

NEW! Voice Recording

Create Set