Week 2 - Lesson 1.7 Electrons

Question 1

Watch out! Lightning is extremely dangerous. A single bolt of lightning can carry a billion volts of electricity. That’s
enough energy to light a 100-watt light bulb—for three months! As impressive as it is, lightning is nothing more
than a sudden flow of extremely tiny particles. What are the particles that flow in a lightning bolt? The answer is
electrons.

Answer 1

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Question 2

What are electrons

Answer 2

Electrons are one of three main types of particles that make up atoms. The other two types are protons and neutrons.
Unlike protons and neutrons, which consist of smaller, simpler particles, electrons are fundamental particles that do
not consist of smaller particles. They are a type of fundamental particles called leptons. All leptons have an electric
charge of -1 or 0.

Question 3

These are extremely small. The mass of an ____ is only about 1/2000 the mass of a proton or neutron, so
e____ contribute virtually nothing to the total mass of an atom.

Answer 3

Electrons

Question 4

Where Are Electrons?

Answer 4

Unlike protons and neutrons, which are located inside the nucleus at the center of the atom, electrons are found
outside the nucleus. Because opposite electric charges attract each other, negative electrons are attracted to the
positive nucleus. This force of attraction keeps electrons constantly moving through the otherwise empty space
around the nucleus. The Figure shown 1.16 is a common way to represent the structure of an atom. It shows the
electron as a particle orbiting the nucleus, similar to the way that planets orbit the sun

Question 5

The atomic model above is useful for some purposes, but it’s too simple when it comes to the location of electrons.
In reality, it’s impossible to say what path an electron will follow. Instead, it’s only possible to describe the chances
of finding an electron in a certain region around the nucleus.

Answer 5

Orbitals

Question 6

Q: How many electrons can there be in each type of orbital shown above

Answer 6

A: There can be a maximum of two electrons in any orbital, regardless of its shape.

Question 7

Q: Where is the nucleus in each orbital?

Answer 7

A: The nucleus is at the center of each orbital. It is in the middle of the sphere in the S orbital and in the pinched
part of the P orbital.

Question 8

Electrons are located at fixed distances from the nucleus, called energy levels. You can see the first three ____ in the Figure 1.18. The diagram also shows the maximum possible number of electrons at each energy level.

Answer 8

Energy level

Question 9

Electron at lower energy levels, which are closer to the nucleus, have less energy. At the lowest energy level,
which has the least energy, there is just one orbital, so this energy level has a maximum of

Answer 9

2

Question 10

Only when a lower energy level is full are electrons added to the next higher energy level. Electrons at higher
energy levels, which are farther from the nucleus, have more energy. They also have more orbitals and greater
possible numbers of electrons

Answer 10

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Question 11

Electrons at the outermost energy level of an atom are called ______ They determine many of
the properties of an element. That’s because these electrons are involved in chemical reactions with other
atoms. Atoms may share or transfer _____. Shared electrons bind atoms together to form chemical
compounds.

Answer 11

Valence electron

Question 12

If an atom has 12 electrons, how will they be distributed in energy levels?

Answer 12

A: The atom will have two electrons at the first energy level, eight at the second energy level, and the remaining two
at the third energy level

Question 13

Q: Sometimes, an electron jumps from one energy level to another. How do you think this happens?

Answer 13

A: To change energy levels, an electron must either gain or lose energy. That’s because electrons at higher energy
levels have more energy than electrons at lower energy levels.

Question 14

This are one of three main types of particles that make up the atom. They are extremely small and have
an electric charge of -1. All atoms have the same number of electrons as protons.

Answer 14

Electrons

Question 15

_____ are attracted to the positive nucleus. This force of attraction keeps electrons constantly
moving around the nucleus. The region where an electron is most likely to be found is called an _____.

Answer 15

Negative electron

Orbital

Question 16

These are located at fixed distances from the nucleus, called energy levels. ____ at lower energy levels
have less energy than ____ at higher energy levels

Answer 16

Electrons

Question 17

This have an electric charge of -1, which is
equal but opposite to the charge of proton, which is +1. All atoms have the same number of ___ as protons, so
the positive and negative charges “cancel out,” making atoms electrically neutral.

Answer 17

Electron

Question 18

The region where an electron is most likely to be
is called an orbital. Each orbital can have at most two electrons. Some orbitals, called

Answer 18

P orbitals, are shaped like
spheres, with the nucleus in the center. An S orbital is pictured in Figure 1.17. Where the dots are denser, the chance
of finding an electron is greater. Also pictured in Figure 1.17 is a P orbital. P orbitals are shaped like dumbbells,
with the nucleus in the pinched part of the dumbbell