Grab a your binder and immediately take a seat
5. The most abundant isotope of lead contains 82
protons and 124 neutrons packed closely together
in the nucleus. Why do protons stay together in
the nucleus rather than fly apart?
a. Electrons in neighboring atoms neutralize repulsive
forces between protons.
b. Neutrons effectively block the protons and keep
them far apart to prevent repulsion.
c. Electrostatic forces between neutrons and protons
hold the nucleus together.
d. Nuclear forces overcome repulsive forces between
protons in the nucleus.
Write a complete sentence about why it is correct!
What are isotopes?
atoms of the same element that have different
numbers of neutrons.
# protons = atomic number
# neutrons = atomic mass – atomic number
# electrons = # of protons
Two ways to express?
1. Element name, hyphen, atomic mass
Helium – 4
2. Element symbol, atomic mass, atomic number
number 2 He
What is the same?
The number of protons = atomic number
The number of electrons
What is the different?
The number of neutrons
The atomic mass
Groups of 4
Do not eat the skittles!
One person will build the isotope, while the others
watch and give feedback
Then, all students will draw on their own paper
Finally, students will be asked to express the
isotope in an alternative way
1. An isotope is a
a. an atom of an element with the same number of neutrons
but different numbers of protons
b. an atom of an element with the same number of protons
but different numbers of neutrons
c. an atom of an element with the same number of protons
but different numbers of electrons
d. an atom with a very small amount of strong force
2. The isotope Boron-12 has an atomic mass of
3. The isotope Carbon-14 has
a. one more electron than Carbon-12.
b. two more protons than Carbon-12.
c. a lower atomic mass than Carbon-12.
d. two more neutrons than Carbon-12.
4. Which of the following is an alternative way to
5. Boron-13 has
a. 13 protons, 8 neutrons, and 5 electrons
b. 5 protons, 13 neutrons, and 5 electrons
c. 5 protons, 8 neutrons, and 7 electrons
d. 5 protons, 8 neutrons, and 5 electrons