Atoms and Ions Activity

Atoms and Ions Activity Name ______Date ______Period _____

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 your teacher demonstrate static electric charge, using balloons and/or other materials. Record some observations below.

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. Refer to Section 13-1, pages 430-432 to help you answer the following questions. 8. In the balloon experiment, what evidence is there that “there must be 2 types of charges”?

9. Why did the author 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. Refer to Figure 13-5. What must be true about the strength of electrical forces compared to the strength of gravity? 20.

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 ______(protons or electrons?), so there are more ______(positive there are more ______(positive or negative?) particles; the opposite charges don’t or negative?) particles; the opposite charges don’t “cancel out” any more. “cancel out” any more.

21. 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?