Web Lab 5.2, 5.3 – Atom Builder

Purpose: To learn about the elementary particles making up an atom and to apply the rules for building a stable atom to make a carbon atom.

Background:

On the periodic table, the number of protons in an atom of an element is given by the atomic number.

Mass number gives the number of protons and neutrons in an atom. Different isotopes of an element have different numbers of neutrons in their nuclei. The mass number of the most common isotope found in nature can most often be determined by rounding off the atomic mass given on the periodic table (which is a weighted average mass of the atoms in a naturally occurring sample of the element).

A neutral atom has the same number of protons and electrons.

Isotopes of elements can be given by the chemical symbol-mass number or by the chemical symbol preceded by the mass number as a superscript and the atomic number as a subscript. For example lithium-6 and lithium-7 can be written like

Both isotopes of lithium have 3 protons. Lithium-6 has 6-3=3 neutrons and Lithium-7 has 7-3=4 neutrons.

Hypothesis:

According to the periodic table, carbon’s atomic number is ____ and its atomic mass is _____. A neutral, stable atom of the most common isotope of carbon will have ____ protons, ____ neutrons, and _____ electrons because _____________________________

_______________________________________________________________________.

Procedure:

1. Go to http://www.pbs.org/wgbh/aso/tryit/atom/index-nojs.html

2. Read The Atom Builder Guide to Elementary Particles and The Atom Builder Guide to Building a Stable Atom.

3. Following the rules for building a stable atom, open the Atom Builder simulation and build a carbon atom. In the data section, draw each neutral, stable atom of each new element that you form along your “journey” (show the locations and numbers of the particles) and fill in the information for that element.

Data - elements formed:

Questions & Conclusions:

1. What two elementary particles make up an atom?

2. Where are the electrons found? What is the charge of an electron?

3. Where are protons and neutrons found? What are their charges?

4. How many quarks are required to make a nuclear particle (i.e. a proton or a neutron)?

5. What charge does an up quark have? What charge does a down quark have?

6. What quarks make up a proton? Show how the charges of quarks in a proton add up to its total charge.

7. What quarks make up a neutron? Show how the charges of quarks in a neutron add up to its total charge.

8. What elementary force counteracts the tendency of positively-charged protons to repel each other and also holds together the quarks that make up protons and neutrons?

9. How many electrons are allowed in the

a) first shell?

b) second shell?

10. What is the charge of a stable atom?

11. When is an atom ionized? What happens if an atom becomes too ionized?

12. When does an atom become radioactive?

13. What happens if you put an electron in the outer shell before the inner shell is full?

14. When does an atom change into another element?