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Date: ________________________
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Student Exploration: Element Builder
Vocabulary (see the end of the packet): atom, atomic number, electron, electron dot diagram,
element, energy level, ion, isotope, mass number, neutron, nucleus, periodic table, proton,
radioactive, valence electrons
Prior Knowledge Questions (Do these BEFORE using the Gizmo.)
1. What are some of the different substances that make up a pizza? _____________________
_________________________________________________________________________
2. What substances make up water? _____________________________________________
3. What substances make up an iron pot? _________________________________________
Elements are pure substances that are made up of one kind of atom. Pizza is not an element
because it is a mixture of many substances. Water is a pure substance, but it contains two kinds
of atom: oxygen and hydrogen. Iron is an element because it is composed of one kind of atom.
Gizmo Warm-up
Atoms are tiny particles of matter that are made up of
three particles: protons, neutrons, and electrons. The
Element Builder Gizmo™ shows an atom with a single
proton. The proton is located in the center of the atom,
called the nucleus.
1. Use the arrow buttons ( ) to add protons, neutrons,
and electrons to the atom. Press Play (
).
A. Which particles are located in the nucleus?
_________________________________
B. Which particles orbit around the nucleus?
__________________________________
2. Turn on Show element name. What causes the element name to change? _____________
_________________________________________________________________________
Activity A:
Subatomic
particles
Get the Gizmo ready:
 Use the arrows to create an atom with two protons,
two neutrons, and two electrons.
 Turn on Show element name.
Question: What are the properties of protons, neutrons, and electrons?
1. Observe: Turn on Show element symbol and Element
notation. Three numbers surround the element symbol: the
mass number (A), electrical charge (no number is displayed if
the atom is neutral), and the atomic number (Z).
2. Investigate: Watch how the numbers change as you add or
remove particles.
A. Which number is equal to the number of protons in the atom? __________________
B. How can you calculate the number of neutrons (N) in an atom? _________________
___________________________________________________________________
C. Which particle (proton, neutron, or electron) has a positive charge? ______________
Negative charge? ______________
No charge at all? ______________
3. Analyze: An isotope is an alternative form of an element. Each isotope of an element has
the same number of protons, but a different number of neutrons. The isotope is represented
by the atomic symbol and mass number, such as He-4. Some isotopes are stable, while
others are radioactive, which means the atoms decay over time and emit radiation.
A. What are the stable isotopes of carbon? ___________________________________
B. What are the stable isotopes of nitrogen? __________________________________
C. List two radioactive isotopes of oxygen: ___________________________________
4. Practice: Use the Gizmo to answer the following questions.
A. How many electrons are in a neutral atom of lithium? ___________
B. How many neutrons are in an atom of Mg-25? ___________
C. What is the mass number of an atom with 5 protons and 7 neutrons? ___________
D. An ion is a charged atom. How many electrons are in O2-? ___________
E. How many electrons are in Mg2+? ___________
Activity B:
Get the Gizmo ready:
Electron
configurations
 Create a neutral hydrogen atom (1 proton, 0
neutrons, 1 electron).
Question: How are electrons arranged around the nucleus of an atom?
1. Observe: Add electrons to your atom until you have used all the available electrons. How
are the electrons arranged? __________________________________________________
_________________________________________________________________________
2. Analyze: Electrons are arranged in orbits called energy levels, shown in the Gizmo.
A. How many electrons can fit in the first energy level? ___________
B. How many electrons can fit in the second energy level? ___________
C. How many electrons can fit in the third energy level? ___________
3. Observe: Click Reset (
). The electrons in the outermost orbit, called valence electrons,
help to create chemical bonds. Create a lithium atom (3 protons, 4 neutrons, 3 electrons).
How many valence electrons are in a neutral lithium atom? ___________
4. Diagram: Turn on Show electron dot diagram. The valence electrons of an atom are
shown in an electron dot diagram. Each dot represents a valence electron.
Draw the electron dot diagram for neutral lithium: ___________
5. Practice: Turn off Show electron dot diagram. Use the Gizmo to create a neutral atom of
each of the following elements. Draw an electron dot diagram for each. When you are
finished, turn on Show electron dot diagram and check your answers.
H
He
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
6. Extend your thinking: Many properties are determined by the number of valence electrons.
Which element probably has similar properties to lithium? _________ Beryllium? _________
Explain: __________________________________________________________________
Get the Gizmo ready:
Extension:
The periodic table
 Create a neutral hydrogen atom.
 If you have access to a periodic table, open it now.
(Not required.)
Question: The 117 or so known elements are arranged in the periodic table. Why does
the periodic table have the shape it has?
1. Form a hypothesis: Look at the first three rows of the periodic table below.
Why do you think the elements are arranged the way that they are? ___________________
_________________________________________________________________________
2. Draw diagrams: Create an electron dot diagram for each of the elements below. Use the
Gizmo to help you do this. To check your work, turn on Show electron dot diagram.
H
He
Li
Be
B
C
N
O
F
Ne
Na
Mg
Al
Si
P
S
Cl
Ar
3. Analyze: What do the elements in each column of the periodic table have in common?
_________________________________________________________________________
_________________________________________________________________________
4. Draw conclusions: How is the periodic table organized? ____________________________
_________________________________________________________________________
_________________________________________________________________________
_________________________________________________________________________
Vocabulary: Element Builder
Vocabulary



Atom – the basic unit of matter.
o
An atom is the smallest particle of an element that
still has all the properties of the element.
o
Atoms are made up of smaller particles called
protons, neutrons, and electrons. The smaller
electrons orbit around a central nucleus of protons
and neutrons.
Atomic number – the number of protons in the nucleus of an atom.
o
Elements are distinguished from one another by their atomic numbers.
o
For example, any atom with two protons is an atom
of helium.
o
The symbol for the atomic number is Z.
o
In an element symbol, the atomic number is shown
at lower left.
Electron – a negatively charged particle that moves around the nucleus.
o

Electron dot diagram – a diagram that shows the element symbol surrounded by dots
representing valence electrons.
o

The mass of an electron is less than one thousandth of the mass of a proton.
For example, the electron dot diagram at right shows that neutral
helium atoms have two valence electrons.
Element – a pure substance that cannot be broken down into simpler substances by
ordinary chemical means.
o
Elements are made of one type of atom.
o
Atoms of different elements are distinguished by the number of protons in the
nucleus. For example, all carbon atoms have 6 protons.

Energy level – a particular region where electrons can orbit a nucleus.

Ion – an atom that has an electrical charge because it has gained or lost electrons.
o
An atom with more protons than electrons is a
positively charged ion, or cation.
o
An atom with more electrons than protons is a
negatively charged ion, or anion.
o
In an element symbol, the electric charge is shown
at upper right.




Isotope – one of several forms of the same element.
o
All isotopes of a given element have the same number of protons, but differ in the
number of neutrons.
o
Most isotopes are radioactive. Usually only one or two stable isotopes exist for a
given element.
Mass number – the number of protons plus neutrons in the nucleus of an atom.
o
For example, the mass number of helium is 4 (2
protons and 2 neutrons).
o
The symbol for the mass number is A.
o
In an element symbol, the mass number is shown
at upper left.
Neutron – a particle with no charge located in the nucleus of an atom.
o
Neutrons have slightly more mass than protons.
o
The number of neutrons is described by the neutron number, N.
o
To find the number of neutrons, subtract the atomic number from the mass
number.
Nucleus – the positively charged, dense center of an atom.
o
The nucleus contains protons and neutrons.

Periodic table – a chart that organizes the chemical elements based on their properties.

Proton – a positively charged particle located in the nucleus of an atom.


o
Protons have slightly less mass than neutrons.
o
The number of protons determines the element.
Radioactive – capable of releasing radiation.
o
In a radioactive atom, the nucleus can spontaneously decay and emit particles
and/or light. These emissions are called radiation.
o
The energy released by radioactive substances can be harnessed to produce
electricity in a nuclear power plant. This energy also can be used to create a
massive explosion in a nuclear bomb.
o
If the emissions change the number of protons in the nucleus, the atom becomes
a different element.
Valence electrons – electrons found in the outermost energy level of an atom.