Chapter 4- The Atom

Question 1

Define an atom

Answer 1

An atom is the smallest building block of matter.

Question 2

Define atomic mass unit (a.m.u)

Answer 2

One-twelfth of the mass of a carbon-12 atom.

Question 3

Define an isotope

Answer 3

An atom with the same number of protons but a different number of neutrons in its nucleus.

Question 4

Define relative atomic mass

Answer 4

The mass of the element compared with the mass of a carbon-12 atom.

Question 5

Define electron configuration

Answer 5

The arrangement of electrons in an atom.

Question 6

Define Pauli’s exclusion principle

Answer 6

Electrons of opposite spin occupy the same orbital.

Question 7

Define the Hund’s rule

Answer 7

Electrons enter orbitals singly before pairing up.

Question 8

Define valence electrons

Answer 8

The electrons in the outermost energy level of the atom that will determine how an atom will react in a chemical reaction.

Question 9

Define the term core electrons

Answer 9

The remaining electrons that make up the atom.

Question 10

What are the 3 fundamental particles in atoms?

Answer 10

• Protons
• Neutrons
• Electrons

Question 11

Which of the particles contribute to mass and volume of an atom?

Answer 11

Protons and neutrons contribute to the mass of an atom and electrons contribute to the volume of an atom.

Question 12

What is holding the particles in the nucleons?

Answer 12

Strong nuclear forces are holding the particles together and they are so strong they overcome repulsive forces the protons have on each other.

Question 13

When does an atom bomb occur?

Answer 13

An atom bomb occurs when a nucleus is split because a lot of energy was released.

Question 14

TRUE OR FALSE

Chemical reactions influence both the nucleus and electrons.

Answer 14

False: chemical reactions only influence the electrons, not the nucleus.

Question 15

Describe the atomic number (z)

Answer 15

• The number of protons in an atom
• Elements are arranged on the table in order of atomic numbers.
• Element’s unique characteristics/properties are due to the amount of protons the element contains
• It is usually the small number.

Question 16

Describe the atomic mass number (A)

Answer 16

• Tells us how many neutrons there are in the nucleus.

- Number of neutrons= Atomic mass number- number of protons.

Question 17

What is nuclear notation?

Answer 17

When the mass number and atomic number change position in the nuclear notation.

Question 18

Which energy levels are further away from the nucleus?

Answer 18

The higher energy levels.

Question 19

How do the electrons move in the energy levels?

Answer 19

Electrons can move to higher energy levels by absorbing energy. They can drop to lower energy levels by releasing energy.

Question 20

How do electrons move so fast?

Answer 20

The energy the electrons have determine the speed of their movement.

Question 21

In what order to the electrons fill the orbitals.

Answer 21

Electrons always fill the lowest energy level first before filling the next higher energy level.

Question 22

Explain the energy shells from lowest to highest.

Answer 22

1st electron shell(lowest energy level)- closest to the nucleus; contains max of 2 electrons. ( lowest amount of energy).
2nd energy level- contains max of 8 electrons.
3rd energy level- contains max of 18 electrons.
4th energy level- contains max of 32 electrons, these electrons contain the most energy.

Question 23

What does the electron configuration describe?

Answer 23

Describes the amount of electrons the atoms contains in each of its orbitals

Question 24

Why do noble gasses not have any valence electrons?

Answer 24

Because they do not react with other atoms.

Question 25

What are core electrons?

Answer 25

Remain attached to the atom during chemical reactions. They require an enormous amount of energy to remove them.