Week 2 - Lesson 1.6 Neutrons Flashcards
The arrow in this photo is pointing to a star that doesn’t look like much compared with some of the other stars in the
picture. It’s certainly much smaller than most other stars. In fact, it’s only about 20 kilometers in diameter. Compare
that with the 1.4-million-kilometer diameter of our own sun. Despite its small size, however, this star has greater
mass than the sun, making it incredibly dense. It also has tremendous gravity. In fact, gravity on its surface is about
2 × 1011 times the gravity we feel on Earth! What type of star is it? It’s called a neutron star. That’s because it
consists solely of neutrons.
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What Is a Neutron?
A neutron is one of three main particles that make up the atom. The other two particles are the proton and electron.
Atoms of all elements—except for most atoms of hydrogen—have neutrons in their nucleus. The nucleus is the
small, dense region at the center of an atom where protons are also found. Atoms generally have about the same number of neutrons as protons. For example, all carbon atoms have six protons and most also have six neutrons. A
model of a carbon atom is shown in the Figure 1.14.
Unlike protons and electrons, which are electrically charged, this have no charge. In other words, they are
electrically neutral. That’s why the_____in the diagram above are labeled n0
. The zero stands for “zero charge.”
The mass of a ____ is slightly greater than the mass of a proton, which is 1 atomic mass unit (amu). (An atomic
mass unit equals about 1.67 × 10−27 kilograms.) A neutron also has about the same diameter as a proton, or 1.7 ×
10−17 meters.
neutron
All the atoms of a given element have the same number of protons and electrons. The number of _____, however,
may vary for atoms of the same element. For example, almost 99 percent of carbon atoms have six neutrons, but
the rest have either seven or eight neutrons. Atoms of an element that differ in their numbers of _____ are called
isotopes. The nuclei of these isotopes of carbon are shown in the Figure 1.15. The isotope called carbon-14 is used
to find the ages of fossils.
Neutrons
Q: Notice the names of the carbon isotopes in the diagram. Based on this example, infer how isotopes of an element
are named
A: Isotopes of an element are named for their total number of protons and neutrons.
The element oxygen has 8 protons. How many protons and neutrons are there in oxygen-17?
A: Oxygen-17—like all atoms of oxygen—has 8 protons. Its name provides the clue that it has a total of 17 protons
and neutrons. Therefore, it must have 9 neutrons (8 + 9 = 17).
This consist of fundamental particles known as quarks and gluons. Each neutron contains three quarks, as
shown in the diagram below. Two of the quarks are called down quarks (d) and the third quark is called an up quark
(u). Gluons (represented by wavy black lines in the diagram) are fundamental particles that are given off or absorbed
by quarks. They carry the strong nuclear force that holds together quarks in a ___
neutrons
This is one of three main particles that make up the atom. It is found in the nucleus and is neutral in
electric charge. It has about the same mass and diameter as a proton. These are found in all atoms except
for most atoms of hydrogen.
Neutron
All the atoms of a given element have the same number of protons and electrons, but they may vary in their
numbers of neutrons. Atoms of the same element that differ in their numbers of neutrons are called .
Isotopes
This consist of fundamental particles known as quarks and gluons. Gluons carry the strong nuclear force
that binds together the quarks in a neutron.
Neutron
This consist of fundamental particles known as quarks and gluons. Each neutron contains three quarks, as
shown in the diagram below. Two of the quarks are called
down quarks (d) and the third quark is called an up quark
(u). Gluons (represented by wavy black lines in the diagram) are fundamental particles that are given off or absorbed
by quarks. They carry the strong nuclear force that holds together quarks in a neutron
