L3 - The Periodic Table of Elements Flashcards

1
Q

When was Dobereiner’s Law of Triads formed?

A

1817

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2
Q

Describe Dobereiner’s Law of Triads.

A

Organised elements in groups of three based on physical and chemical properties - found that the atomic masses of the 3 elements formed a pattern.

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3
Q

When was Newlands’ Law of Octaves formed?

A

1864

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4
Q

Describe Newlands’ Law of Octaves.

A

Organised elements in increasing order of atomic mass, and noticed that every 8th element exhibited similar properties.

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5
Q

When was Mendeleev’s Periodic Table formed?

A

1869

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6
Q

Describe Mendeleev’s Periodic Table.

A
  • Arranged elements known at that time in order of relative atomic mass
  • Realised that physical and chemical properties of elements were related to their atomic mass in a ‘periodic’ way, and arranged them so that groups of elements with similar properties were in vertical columns in his table
  • Left gaps in horizontal rows; assumed it meant that these elements had not yet been discovered
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7
Q

When was Seaborg’s Periodic Table formed?

A

1940

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8
Q

Describe Seaborg’s Periodic Table.

A
  • Expanded beyond Mendeleev’s initial 63 elements
  • Vertical columns = groups
  • Horizontal rows = rows
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9
Q

How is the Periodic Table arranged?

A
  • Elements are arranged in order of atomic number, from left to right
  • Progression runs from metals to non-metals across each period
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10
Q

Which group are the noble gases found in?

A

Group 8

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11
Q

State the Periodic Law.

A

“Properties of elements are periodic functions of their atomic numbers.”

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12
Q

What happens when elements are arranged in order of increasing atomic number?

A

There is a periodic pattern in their physical and chemical properties.

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13
Q

What are ‘families’ of elements?

A

Elements that share certain characteristics, not only in terms of observable behaviour, but also atomic structure.

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14
Q

State the common classifications of elements on the Periodic Table.

A
  • Alkali Metals
  • Alkaline Earth Metals
  • Transition Metals
  • Lanthanides
  • Actinides
  • Noble Gases
  • Non-Metals
  • Metalloids
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15
Q

Describe Group 1: Alkali Metals.

A
  • Silver coloured
  • Soft metals
  • Highly reactive
  • Rarely found in elemental form in nature
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16
Q

Describe Group 2: Alkaline Earth Metals.

A
  • Silver coloured
  • Soft metals
  • Reactivity similar to alkali metals
17
Q

Describe Group 7 (17): Halogens.

A
  • Highly reactive
  • Toxic
  • Gases
  • Low boiling / melting materials
18
Q

Describe Group 8 (18): Noble Gases.

A
  • Chemically inert
  • Non-metallic
  • Gaseous at standard conditions
19
Q

Describe Metalloids.

A
  • 6 elements

- Properties of both metals and non-metals

20
Q

Describe Transition Metals.

A
  • High densities, melting and boiling points
  • Form coloured compounds and complex ions
  • Variable valencies
  • Ions readily undergo oxidation / reduction
  • Can use electrons from two outer orbitals for combination with other elements
21
Q

What are the Lanthanides?

A

15 elements with atomic numbers 57 - 71

22
Q

Describe the Lanthanides.

A
  • Also known as rare Earth metals
  • Shiny and silvery-white
  • Stain easily when exposed to air
  • High melting and boiling points
23
Q

What are the Actinides?

A

15 elements with atomic numbers 89 - 103

24
Q

Describe the Actinides.

A
  • Radioactive
  • Very dense metals
  • Distinctive structures
  • Numerous allotropes may be formed
  • Combine directly with most non-metals
25
Q

What are the Non-Metals?

A

Groups 14-16 of the periodic table

26
Q

Describe the Non-Metals.

A
  • Not able to conduct electricity or heat very well
  • Very brittle
  • Cannot be rolled into wires / pounded into sheets
  • No metallic lustre and do not reflect light
27
Q

Describe the properties of elements in line with the general characteristics of groups.

A
  • All elements of a given group possess very similar physical and chemical properties
  • Regular gradation in properties when moving from top to bottom in a group
  • Patterns in properties can also be seen going across a period
28
Q

Describe the size of atoms in line with the general characteristics of groups.

A
  • Increases on descending a group
29
Q

Describe the metallic character of elements in line with the general characteristics of groups.

A
  • Increases when moving from top to bottom in a group

- Apparent in groups 12, 13 and 14

30
Q

Describe the reactivity of elements in line with the general characteristics of groups.

A
  • Metals become more reactive on descending a group

- Non-metals become less reactive

31
Q

Describe the number of electron shells in line with the general characteristics of groups.

A
  • Equal to the number of the period to which the element belongs
  • Going down a group, the number of electron shells increases by one at each step
32
Q

Describe the number of valence electrons in line with the general characteristics of groups.

A
  • Number of electrons in the outer shell of an atom is unchanged on moving down a given group
33
Q

Describe valency in line with the general characteristics of groups.

A
  • Valencies of all the elements in a group are generally the same
34
Q

How are valencies calculated?

A
  • Groups 1 - 4: Valency = Group Number

- Groups 4 - 8: Valency = (8 - Group Number)

35
Q

Define Valency.

A

The number of chemical bonds formed by an atom.

36
Q

The valency of a monoatomic ion is equal to its ______.

A

Charge

37
Q

Which elements have multiple valencies?

A
  • Phosphorus (P): Valency = 3/5
  • Nitrogen (N): Valency = 3/5
  • Transition metals
  • Heavier elements, such as Lead (Pb): Valency = 2/4
38
Q

Define Empirical Formula.

A

Expresses elemental composition of a compound as a simple whole number ratio.

39
Q

Define Molecular Formula.

A

The exact number of each type of atom present in one molecule of the compound.