The Periodic Table (chpt. 4)

Question 1

Greeks

Answer 1

Elements are earth, air, fire, water

Question 2

Who defined elements

Answer 2

Robert Boyle

Question 3

Robert Boyle

Answer 3

Defined elements

Question 4

Element

Answer 4

An element is a substance that cannot be split into simpler substances by chemical means

Question 5

Humphrey Davy

Answer 5

Discovered many elements (through electrolysis - passing electricity through their compounds)

Question 6

Triad

Answer 6

A group of 3 elements with similar chemical properties.
The atomic weight of the middle element is approximately equal to the average of the other two.
E.g. Li, Na, K

Question 7

Practice writing electron configurations of elements and ions

Question 8

Atomic number

Answer 8

The number of protons in the nucleus of an atom
Doesn’t change

Question 9

Atomic mass

Answer 9

Sum of the protons and neutrons in the nucleus

Question 10

Isotopes

Answer 10

Atoms of the same element (same atomic number) that have different mass numbers due to the different numbers of neutrons in the nucleus
E.g. C-12, C-13

Question 11

What were Dobrereiners triads

Answer 11

Triads
Chemicals have similar properties grouped in the threes and the middle one has a mass approximately equal to the average of the other two

Question 12

What were Newlands octaves
Flaws?

Answer 12

Every eighth element had properties similar to the first

Didn’t leave gaps for undiscovered elements
Noble gases were undiscovered

Question 13

How did Mendeleev arrange the elements in the periodic table

Answer 13

Arranged known elements according to increasing atomic weight / atomic mass
Left gaps for undiscovered elements

Question 14

Why did Mendeleev not include the noble gases

Answer 14

They were undiscovered

Question 15

Atomic number

Answer 15

Number of protons in the nucleus of an atom

Question 16

Relative atomic mass

Answer 16

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

Question 17

Relative atomic mass

Answer 17

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

Question 18

Mendeleevs periodic table

Answer 18

• Arranged known elements in periodic lines according to atomic weight
• Left gaps
• Reversed order of some elements so similar properties were grouped together (e.g. iodine & tellurium)

Question 19

How is the modern periodic table arranged

Answer 19

In order of increasing atomic number

Question 20

Mass number

Answer 20

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

Question 21

Electronegativity

Answer 21

The relative attraction an atom in a molecule has for the shared pair of electrons in a covalent bond

Question 22

Isotope

Answer 22

Atoms of the same element that have different mass numbers due to the different number of neutrons in the nucleus

Question 23

Henry moseley

Answer 23

Discovered a method of finding the number of protons in the nucleus (atomic number)

Question 24

Who discovered the atomic number

Answer 24

Henry Moseley (x-ray)

Question 25

Who defined the element

Answer 25

Robert boyle

Question 26

What is an element

Answer 26

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

Question 27

Mendeleev vs the modern periodic table

Answer 27

Atomic weight vs atomic number
Only 60 elements vs over 100 elements
Gaps vs no gaps
Transition elements not separated vs transition elements in separate block

Question 28

Steps of mass spectrometer

Answer 28

1. Vaporisation
   Sample is turned into a vapour/gas
2. Ionisation
   Atoms/molecules are turned into ions (charged atoms)
   High energy electrons are fired to produce positive ions
3. Acceleration
   Positive ions are passed through negatively charged plates which accelerate them
4. Separation
   Ions are made to move in a curved path using a magnetic field
   Lighter particles are easier to deflect so they are pushed further off course than the heavier ions
   Meaning the ions are split into a number of beams depending on the mass of the particles
5. Deflection
   Positive ions fall on the detector ( a very sensitive instrument that responds to the number of ions hitting it)
   Signal is amplified and viewed on a computer screen - mass spectrum

Question 29

Uses of mass spectrometry

Answer 29

Identify presence of isotopes
Measure relative abundance of isotopes
Measure relative molecular masses
Identify unknown compounds
Used in forensic labs

Question 30

The principle of mass spectrometry

Answer 30

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

Question 31

Aufbau principle

Answer 31

When building up the electron configuration of an atom in its ground state, the electrons occupy the lowest available energy levels

Question 32

Hund’s rule of maximum multiplicity

Answer 32

States that when two or more orbitals of equal energy are available, the electrons occupy them singly before filling them in pairs

Question 33

The Pauli exclusion principle

Answer 33

States that no more than two electrons must occupy an orbital and they must have opposite spin