4.1 Atomic structure and the periodic table

Question 1

What is an atom?

Answer 1

An atom is the smallest unit of an element, made up of protons, neutrons, and electrons.

Question 2

What is the charge of a proton?

Answer 2

Positive.

Question 3

What is the charge of a neutron?

Answer 3

Neutral (no charge).

Question 4

What is the charge of an electron?

Answer 4

Negative.

Question 5

Where is the mass of an atom concentrated?

Answer 5

The nucleus, which contains protons and neutrons.

Question 6

What is the relative mass of a proton?

Answer 6

1

Question 7

What is the relative mass of a neutron?

Answer 7

1

Question 8

What is the relative mass of an electron?

Answer 8

Very small (close to 0).

Question 9

What is the atomic number?

Answer 9

The number of protons in the nucleus of an atom.

Question 10

What is the mass number?

Answer 10

The total number of protons and neutrons in an atom’s nucleus.

Question 11

What is an isotope?

Answer 11

Atoms of the same element with the same number of protons but different numbers of neutrons.

Question 12

How do you calculate the number of neutrons in an atom?

Answer 12

Number of neutrons = mass number - atomic number.

Question 13

What is the electronic configuration of an atom?

Answer 13

The arrangement of electrons in the electron shells around the nucleus.

Question 14

What is the periodic table?

Answer 14

A table that arranges elements based on their atomic number, with elements in the same column having similar chemical properties.

Question 15

What are groups in the periodic table?

Answer 15

Vertical columns in the periodic table where elements have similar properties.

Question 16

What are periods in the periodic table?

Answer 16

Horizontal rows in the periodic table where properties change progressively across a period.

Question 17

How many groups are there in the periodic table?

Answer 17

18 groups.

Question 18

How many periods are there in the periodic table?

Answer 18

7 periods.

Question 19

What are alkali metals?

Answer 19

Elements in Group 1 of the periodic table (e.g., lithium, sodium, potassium).

Question 20

What are halogens?

Answer 20

Elements in Group 17 of the periodic table (e.g., fluorine, chlorine, bromine).

Question 21

What are noble gases?

Answer 21

Elements in Group 18 of the periodic table (e.g., helium, neon, argon).

Question 22

What is the trend in reactivity of alkali metals down Group 1?

Answer 22

The reactivity increases as you go down the group.

Question 23

What is the trend in reactivity of halogens down Group 17?

Answer 23

The reactivity decreases as you go down the group.

Question 24

What is the trend in boiling points of noble gases down Group 18?

Answer 24

The boiling points increase as you go down the group.

Question 25

What is the outer electron configuration of alkali metals?

Answer 25

One electron in their outer shell.

Question 26

What is the outer electron configuration of halogens?

Answer 26

Seven electrons in their outer shell.

Question 27

What is the outer electron configuration of noble gases?

Answer 27

Eight electrons in their outer shell (except helium, which has two).

Question 28

Why are noble gases unreactive?

Answer 28

They have a full outer electron shell, making them stable.

Question 29

What is a covalent bond?

Answer 29

A chemical bond formed by the sharing of electrons between atoms.

Question 30

What is an ionic bond?

Answer 30

A chemical bond formed when electrons are transferred from one atom to another, creating ions.

Question 31

How are the properties of ionic compounds different from covalent compounds?

Answer 31

Ionic compounds have high melting/boiling points and conduct electricity when molten or dissolved, while covalent compounds usually have lower melting/boiling points and do not conduct electricity.

Question 32

Who developed the first periodic table?

Answer 32

Dmitri Mendeleev.

Question 33

How did Mendeleev arrange elements in his periodic table?

Answer 33

By atomic mass, and he left gaps for undiscovered elements.

Question 34

What did Mendeleev predict about elements?

Answer 34

He predicted the properties of elements that had not yet been discovered.

Question 35

How is the modern periodic table arranged?

Answer 35

By atomic number, rather than atomic mass.

Question 36

Why is the modern periodic table better than Mendeleev’s?

Answer 36

It is arranged by atomic number, which solved the problem of elements not fitting properly when ordered by atomic mass.

Question 37

What is the trend in atomic radius across a period?

Answer 37

The atomic radius decreases as you move across a period from left to right.

Question 38

What is the trend in atomic radius down a group?

Answer 38

The atomic radius increases as you move down a group.

Question 39

What is the trend in ionization energy across a period?

Answer 39

The ionization energy increases as you move across a period from left to right.

Question 40

What is the trend in ionization energy down a group?

Answer 40

The ionization energy decreases as you move down a group.

Question 41

What is electronegativity?

Answer 41

The ability of an atom to attract electrons in a chemical bond.

Question 42

What is the trend in electronegativity across a period?

Answer 42

Electronegativity increases as you move across a period.

Question 43

What is the trend in electronegativity down a group?

Answer 43

Electronegativity decreases as you move down a group.

Question 44

What is the main use of sodium?

Answer 44

Sodium is used in the manufacture of soap, glass, and as a coolant in nuclear reactors.

Question 45

What is the main use of chlorine?

Answer 45

Chlorine is used to disinfect drinking water, in the production of plastics (PVC), and in bleach.

Question 46

What is the main use of argon?

Answer 46

Argon is used in light bulbs and welding because it is an inert gas.

Question 47

What is the main use of helium?

Answer 47

Helium is used in balloons, and as a coolant in cryogenics.

Question 48

What is the main use of iodine?

Answer 48

Iodine is used in disinfectants, in the production of iodized salt, and in medical applications.