SWBAT define and give examples of atoms, molecules, atomic mass unit, and
average atomic mass by asking questions and defining problems with 80%
accuracy; write and interpret symbols that depict atomic number and mass
number of an atom or isotope by developing and using models with 80%
accuracy.
Atoms and Ions Activity
ATOMS: Atoms are electrically neutral, neither positively nor negatively charged. Although atoms have
no net charge, they are composed of smaller particles. Some of these “subatomic” particles do have a
charge. Two subatomic particles are protons and neutrons, which are found in the nucleus of an atom.
The proton has a mass of 1.0 amu (atomic mass unit) and has a charge of +1. The neutron also has a mass
of 1.0 amu, but no charge at all; it is neutral. The atomic mass of an atom is made up of the mass of the
protons and neutrons together. Electrons are subatomic particles found orbiting (moving around) the
nucleus of the atom. Electrons have almost no mass (1/1803 amu) and a charge of –1. Since the atom is
neutral, each atom must have the same number of positive protons and negative electrons.
Atoms of different elements have a unique number of protons. The atomic number of the atom
indicates the number of protons. For example, carbon is atomic number 6. A carbon atom has 6 protons
and therefore six electrons.
1. The simplest atom is an atom of hydrogen. For hydrogen, complete the table below.
Location
How many?
How do you know how many there are?
Protons
Electrons
2. a. Sketch a carbon atom. Label each of the 3 types of particles.
b. Explain why the carbon atom you drew is neutral (has no
charge).
3. What particles most determine the mass of an atom?
4. Use your periodic table to complete the following:
Kind of atom
Symbol
Number of protons
Number of electrons
Oxygen
Neon
Copper
Iron
Gold
Calcium
Sulfur
5. a. Which atom in the table (see #4) has the greatest atomic mass? _______________
b. Which atom in the table has the lowest atomic mass? _______________
c. Why do atoms of different elements have different masses?
IONS: Ions are charged particles. They are atoms that have become either positively or negatively
charged. Being that they are charged atoms, ions have protons, electrons, and neutrons. In an ion,
the positive protons don’t “cancel out” the negative electrons, so the particle is charged. Atoms
become ions in the same way that everyday materials become charged.
•
Watch the video that demonstrates static electric charge, using balloons. Record some
observations below.
https://www.youtube.com/watch?v=oU8Fe6846d4
6. The balloon and the hair started off as neutral materials. A simple model
of a neutral material is shown in the diagram.
a. Does the collection of particles shown at the right have a net (overall)
charge?
Yes or
No
b. Imagine that a negative particle is removed from the set. Draw the
new set and determine the net charge on the new set of particles.
Net charge = _______
c. Imagine that a positive particle is removed from the original set. Draw the new set and determine
the net charge on the new set of particles.
Net charge = _______
7. Materials become charged if they lose or gain charged particles from their atoms.
a. List the charged particles in an atom. ______________ and _______________
b. Think about the locations of the charged particles in an atom. Which type of charged particle do
you think is most likely to be gained or lost? Explain.
8. In the balloon experiment, what evidence is there that “there must be 2 types of charges”?
9. Why did the narrator on the video conclude that the balloons have the same charge?
10. What must be true if an object has no net charge?
11. All matter is composed of atoms. Because of this, objects contain an enormous number of
_____________, _______________, and _____________.
12. What must be true if an object has a net charge?
13. Negatively charged objects have more __________ than ____________.
Positively charged objects have more ___________ than ____________.
14. True or False? An electron and a proton have exactly the same amount of charge.
15. True or False? Protons can be easily transferred from one atom to another.
Explain.
16. In “charging by friction”, one material ____________electrons and becomes negatively charged,
and the other ___________ electrons and becomes positively charged.
17. Go back to #6 on the previous page. Draw a star (*) next to either #6b or #6c to show which
situation actually occurs when a material becomes charged.
18. Just as objects are attracted or repel due to static electric charge, particles interact in the same
manner due to their electrical charges.
a) Use knowledge of charges to explain why electrons would be attracted to the nucleus of an atom.
b) Based on electrical charge, what interaction would you expect for protons in the nucleus of an
atom?
c) Propose an explanation for how the protons are kept together in the nucleus.
19.
When a balloon is rubbed against hair, the hair becomes positively
charged and the balloon becomes negatively charged.
How the hair becomes positively charged.
How the balloon becomes negatively charged.
Atoms in the hair ___________ (lose or gain?)
Atoms in the balloon ___________ (lose or gain?)
________________ (protons or electrons?), so there
________________ (protons or electrons?), so there
are more ___________________ (positive or
are more ___________________ (positive or
negative?) particles; the opposite charges don’t
negative?) particles; the opposite charges don’t
“cancel out” any more.
“cancel out” any more.
20. Just like the balloon and hair attract due to their opposite charges, metal and nonmetal ions
attract due to opposite charges.
a) A sodium atom becomes a positively charged sodium ion. What must have happened for
this to happen?
b) A chlorine atom becomes a negatively charged chloride ion. What must have happened
for this to happen?