Question

4.1 - 4.2 review
read this: for this review you will need: your journal, your phet, and any other resources that helped you to succeed in this content. expect to see the content in a variety of forms. for example it is not enough to have memorized that protons are positive and are in the center of the atom. you will need to be able to recall and use that definition when looking at models, pictures, charts etc.

1. fill in the chart below for each subatomic particle:

particle	location	charge	symbol(s)
			n°
			e- or -

1. based on the chart from question 1, what is the overall charge of the nucleus?
2. where is nearly all of the mass of the atom located? how do you know?
3. which of the three subatomic particles is responsible for identification of the element?
4. can you change the proton count of the atom and still have it be the same element?
5. what is an isotope?
6. which subatomic particle varies and creates isotopes of the same element?
7. what is an ion?
8. which subatomic particle changes to create ions?
9. write a complete sentence that explains what must be true for an atom to be considered electrically neutral.
10. what is the definition of atomic number?
11. how do you calculate mass number?
12. rearrange the equation from question 12 to solve for neutrons.
13. what is the calculation needed to find charge?

Explanation:

Step1: Fill in the chart for subatomic particles

Particle	Location	Charge	Symbol(s)
Neutron	Nucleus	Neutral (0)	n<sup>0</sup>
Electron	Electron - cloud	Negative (-1)	e-

Step2: Calculate overall charge of nucleus

The nucleus contains protons and neutrons. Neutrons are neutral, and protons have a positive charge. So the overall charge of the nucleus is positive, determined by the number of protons.

Step3: Locate mass of atom

Nearly all of the mass of the atom is located in the nucleus. This is because protons and neutrons, which are in the nucleus, have significant mass compared to electrons which have negligible mass.

Step4: Identify element - determining particle

The proton is responsible for the identification of the element. The number of protons (atomic number) is unique to each element.

Step5: Analyze proton - element relationship

You cannot change the proton count of an atom and still have it be the same element. Changing the number of protons changes the atomic number and thus the element.

Step6: Define isotope

An isotope is an atom of the same element that has the same number of protons but a different number of neutrons.

Step7: Identify particle for isotopes

The neutron is the sub - atomic particle that varies and creates isotopes of the same element.

Step8: Define ion

An ion is an atom or molecule that has a net electrical charge due to the loss or gain of electrons.

Step9: Identify particle for ions

Electrons are the sub - atomic particles that change to create ions. Losing electrons creates positive ions (cations), and gaining electrons creates negative ions (anions).

Step10: Explain electrical neutrality

An atom is considered electrically neutral when the number of protons (positive charges) is equal to the number of electrons (negative charges).

Step11: Define atomic number

The atomic number is the number of protons in the nucleus of an atom.

Step12: Calculate mass number

The mass number is calculated by adding the number of protons and the number of neutrons in the nucleus of an atom (Mass Number = Protons + Neutrons).

Step13: Rearrange for neutrons

From Mass Number = Protons + Neutrons, we can rearrange to get Neutrons = Mass Number - Protons.

Step14: Calculate charge

To find the charge of an atom or ion, you calculate the number of protons minus the number of electrons (Charge = Protons - Electrons).

Answer:

1. See filled - in chart above.
2. Positive, determined by number of protons.
3. In the nucleus; protons and neutrons in nucleus have significant mass compared to electrons.
4. Proton.
5. No.
6. An atom of the same element with same number of protons but different number of neutrons.
7. Neutron.
8. An atom or molecule with a net electrical charge due to loss or gain of electrons.
9. Electron.
10. The number of protons must be equal to the number of electrons.
11. The number of protons in the nucleus of an atom.
12. Mass Number = Protons + Neutrons.
13. Neutrons = Mass Number - Protons.
14. Charge = Protons - Electrons.