topic 1 - atomic structure + periodic table

Question 1

Describe the structure of an atom

Answer 1

a nucleus containing protons and neutrons, surrounded by electrons in shells

Question 2

Relative charges of subatomic particles

Answer 2

Protons: +1
Neutrons: 0
Electrons: -1

Question 3

Relative mass of subatomic particles

Answer 3

Protons: 1
Neutrons: 1
Electrons: 0.0005

Question 4

Why do atoms contain an equal number of protons and electrons

Answer 4

The + and - charges cancel each other out, making it stable

Question 5

Describe the nucleus of an atom

Answer 5

very small compared to the overall size of the atom (most of an atom is empty space)

Question 6

Where is most of the mass of an atom concentrated?

Answer 6

Nucleus

Question 7

What does an atoms mass number mean?

Answer 7

Total number of protons and neutrons in it’s nucleus

Question 8

Describe atoms of a given element

Answer 8

They have the same number of protons in the nucleus and this number is unique to each element

Question 9

What are isotopes?

Answer 9

An element that has the same number of protons but a different number of neutrons

Question 10

How do you calculate the numbers of protons, neutrons and electrons in atoms given the atomic number and mass number

Answer 10

Atomic number: number of protons (=number of electrons)

Atomic mass: number of protons and neutrons in an atom

Question 11

What is the result of an isotope’s existence?

Answer 11

The RAM of some elements are not whole numbers

Question 12

What is RAM

Answer 12

The average of the mass numbers of different isotopes, weighted by how common each isotope is

Question 13

How to calculate the RAM of an element?

Answer 13

RAM = ((% of isotope a x mass of isotope a) + (% of isotope b x mass of isotope b)) / 100

Question 14

How did Mendeleev arrange the elements?

Answer 14

In a periodic table by atomic mass and similar chemical properties

Question 15

What could Mendeleev predict?

Answer 15

He used the periodic table to predict the existence and properties of elements not yet discovered

Question 16

Why was some of Mendeleev’s table inaccurate?

Answer 16

He believed the elements were ordered in increasing RAM but this wasn’t always true due to the existence of isotopes

Question 17

What does an element’s atomic number tell us about it?

Answer 17

Tells us how many protons are in its nucleus and where it sits in the periodic table

Question 18

How are elements arranged in the groups and periods of the periodic table?

Answer 18

• By increasing atomic number
• Groups: similar chemical properties
• Periods: same number of electron shells

Question 19

What does an elements position in the periodic table tell us about its electronic configuration?

Answer 19

Group number = electrons in outer shell
Period number = number of electron shells

Question 20

Identify elements as metals or non-metals according to their position in the periodic table

Answer 20

Metals: mostly left/centre of table, because metals only have few electrons in their outer shell
Non-metals: right side of table, have more electrons in outer shell

Question 21

How are cations formed?

Answer 21

Metals lose electrons to form positively charged ions (cations)

Question 22

How are anions formed?

Answer 22

Non-metals gain electrons to form negatively charged ions (anions)

Question 23

What do the dots and crosses represent in dots and cross diagrams?

Answer 23

Dots: non-metals
Crosses: metals

Question 24

What is an ion?

Answer 24

Charged particles made when electrons are transferred

Question 25

What is the charge of an ion?

Answer 25

Number of electrons gained or lost (e.g. 2+ means 2 electrons lost, 2 more protons than electrons, in group 2)

Question 26

Calculate the numbers of protons, neutrons and electrons in simple ions given the atomic number and mass number

Answer 26

Protons: AN = number of protons
Neutrons: MN-AN = number of neutrons
Electrons: for positive ions (Na+) = AN - charge, negative ions (Cl-) = AM + charge

Question 27

Explain the formation of ions in ionic compounds from their atoms (groups 1, 2, 6, 7)

Answer 27

Group 1: Alkali metals - lose electrons to form cations (1+)
Group 2: Alkaline Earth metals - lose electrons to form cations (2+)
Group 6: Chalcogens - gain electrons to form anions (2-)
Group 7: Halogens - gain electrons to form anions (1-)

Question 28

What is the overall charge of an ionic compound?

Answer 28

Zero - stable

Question 29

Name ends in -ate or -ide, what does that mean?

Answer 29

-ate = oxygen and at least one other element
-ide = only one element

Question 30

What determines the formula of an ionic compound?

Answer 30

Balance of positive and negative charges between ions, these ions combine in a way that their charges balance out - making in neutral

Question 31

Explain the structure of an ionic compound

Answer 31

Strong electrostatic forced of attraction between oppositely charged ions acting in all directions, this pattern is called an ionic lattice

Question 32

3 properties of an ionic compound:

Answer 32

1. HMP/HBP - lots of energy is needed to overcome attraction between bonds
2. Soluble on water
3. Conduct electricity (only when molten or dissolved) - ions free to move/carry electric charges

Question 33

What is ionic bonding?

Answer 33

The electrostatic attraction between oppositely charged ions

Question 34

What is a covalent bond?

Answer 34

A shared pair of electrons between two non-metal atoms