Chapter 4 - The Periodic Table

Question 1

Greek philosophers believed there were four elements, what were they?

Answer 1

Earth
Air
Fire
Water

Question 2

What was Robert Boyle’s definition on an element?

Answer 2

A substance that cannot be split into a simpler substance by chemical means

Question 3

What did Humphry Davy do?

Answer 3

○Split water into hydrogen and oxygen using electricity
○Tried this with other compounds
○Discovered potassium in this way in 1807 as globules caught fire during the experiment
○Later extracted calcium from lime
○Also discovered Ba, St and Mg

Question 4

Who arranged elements into triads?

Answer 4

Dobereiner

Question 5

Triad

Answer 5

A group of three elements with similar chemical properties in which the atomic weight (relative atomic mass) of the middle element is approximately equal to the average of the other two

Question 6

Give three examples of Dobereiner Triads

Answer 6

Chlorine, Bromine and Iodine
Calcium, Strontium and Barium
Lithium, Sodium and Potassium

Question 7

Newland’s Octaves

Answer 7

Arrangements of elements in order of increasing atomic weight in which the first and eighth element, counting from a particular element, have similar properties

Question 8

What were the problems with Newland’s Octaves?

Answer 8

►Some groups didn’t match up
►Noble Gases hadn’t been discovered yet, so it should have been every ninth element
►Should have left gaps for undiscovered elements
►Only works for the first 16 elements
►Got a lot of criticism

Question 9

Mendeleev’s Periodic Law

Answer 9

When elements are arranged in order of increasing atomic weight (relative atomic mass), the properties of the elements recur periodically

Question 10

What did Henry Mosely do?

Answer 10

Used x-rays to count protons and discovered that each element had a different and unique number of protons in its nucleus and this is what caused each element to have unique properties

Question 11

Atomic number

Answer 11

Number of protons in the nucleus of that atom

Question 12

Modern Periodic Table

Answer 12

Arrangement of electrons in order of increasing atomic number

Question 13

Modern Periodic Law

Answer 13

When elements are arranged in order of increasing atomic number, the properties of the elements recur periodically, i.e. the properties displayed by an element are repeated at regular intervals in other elements

Question 14

Nucleus (atom)

Answer 14

Dense centre of an atom where protons and neutrons are found

Question 15

Mass number

Answer 15

Sum of the number of protons and neutrons in the nucleus of an atom of that element

Question 16

Isotopes

Answer 16

Atoms of the same element (i.e. they have the same atomic number) that have different mass numbers due to the different number of neutrons in the nucleus

Question 17

What did Francis William Aston do?

Answer 17

Used a mass spectrometer to measure the number of atoms and discovered samples of an element that had atoms of different masses. He also calculated their % abundance in the sample

Question 18

Relative atomic mass

Answer 18

The average of the mass numbers of the isotopes of that element
○as they occur naturally,
○taking their abundances into account and
○expressed on a scale in which the atoms of the carbon-12 isotope have a mass of exactly 12 units

Question 19

What are the stages in a mass sectrometer?

Answer 19

1. Vapourisation
2. Ionisation
3. Acceleration
4. Deflection
5. Detection

Question 20

Principal of Mass Spectrometry

Answer 20

Charged particles moving in a magnetic field are deflected to different extents according to their masses and are thus separated according to their masses

Question 21

What are the uses of a mass spectrometer?

Answer 21

○Identify the presence of isotopes
○Measure the relative abundance of isotopes
○Measure Ar and Mr
○identify unknown compounds like drugs

Question 22

Electron configuration

Answer 22

Shows the arrangement of electrons in an atom of an element

Question 23

How many electrons can the s sublevel hold?

Answer 23

2

Question 24

How many electrons can the p sublevel hold?

Answer 24

6 (two in each p orbital)

Question 25

How many electrons can the d sublevel hold?

Answer 25

10 (two in each d orbital)

Question 26

Aufbau Principal

Answer 26

When building up the electronic configurations of atom in the ground state, electrons occupy the lowest available energy level

Question 27

What order do you fill up orbitals?

Answer 27

1s, 2s, 2p, 3s, 3p, 4s, 3d, 4p, ….

Question 28

What elements break the pattern in the first row of d-block?

Answer 28

Cr

Cu

Question 29

Ions

Answer 29

Are atoms (r groups of atoms) which carry an electric charge because they have either gained or lost one or more electrons

Question 30

How do you write the electronic structure of s- and p-block ions?

Answer 30

Write the electronic structure for the neutral atom and then add (for negative ion) or subtract (for positive ion) electrons

Question 31

Hund’s Rule of Maximum Multiplicity

Answer 31

When two or more orbitals of equal energy are available the electrons occupy them singly before filling them in pairs

Question 32

Paulis Exclusion Principal

Answer 32

No more than two electrons may occupy an orbital and they must have opposite spin

Question 33

Clarify the difference between energy levels, energy sublevels,and individual orbitals

Answer 33

energy levels → n=1, n=2…
energy sublevels → 1s, 2s, 2p…
individual orbitals→ 2px, 2py, 2pz