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Chemistry > The periodic table > Flashcards

The periodic table Flashcards

1
Q

What was the basis for organizing elements before the discovery of protons, neutrons, and electrons?

A

Approximate weights of atoms relative to each other and their physical and chemical properties

Observations made during experiments about how atoms reacted were crucial for this organization.

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2
Q

Who first listed the elements in order of atomic weight and noticed the law of octaves?

A

John Newlands

He observed that every eight elements had similar properties.

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3
Q

What were some limitations of John Newlands’ periodic table?

A

• No gaps for undiscovered elements
• The law of octaves wasn’t always followed
• Some elements were incorrectly grouped based on atomic weight instead of properties.

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4
Q

In what year did Dmitri Mendeleev create a more accurate periodic table?

A

1869

Mendeleev’s table was an improvement over Newlands’ due to his predictive approach.

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5
Q

What two main strategies did Mendeleev use to improve the periodic table?

A

• Left gaps for undiscovered elements by predicting their properties
• Swapped elements that didn’t fit their group based on properties.

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6
Q

How is the modern periodic table organized?

A

In order of atomic number (number of protons)

This organization reflects the discovery of protons, electrons, and neutrons.

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7
Q

What does the arrangement of elements in the same group indicate?

A

They have the same number of electrons in their outer shell.

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8
Q

What determines an element’s reactivity?

A

The number of electrons in their outer shell.

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9
Q

What do elements in the same period have in common?

A

They have the same number of shells/energy levels.

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10
Q

Why is atomic number preferred over atomic weight for organizing the periodic table?

A

Atomic weight didn’t work due to isotopes; atomic number only counts protons.

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11
Q

What feature of the periodic table separates metals from non-metals?

A

A staircase line.

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12
Q

What are some characteristics of metals?

A

• React to form positive ions
• Conduct electricity
• Metal oxides are always basic.

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13
Q

What do non-metals not form when they react?

A

Positive ions

Non-metals typically do not lose electrons to form positive ions.

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14
Q

Which form of carbon conducts electricity?

A

Graphite and graphene

These are exceptions among non-metals.

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15
Q

What type of oxides do non-metals form?

A

Acidic oxides

Non-metals typically produce acidic oxides when they react.

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16
Q

What are the noble gases?

A

Helium, Neon, Argon, Krypton, Xenon, Radon

These elements are known for their inertness due to having a full outer electron shell.

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17
Q

What is the electron configuration of noble gases?

A

8 electrons in the outer shell (except Helium has 2)

A stable arrangement of electrons contributes to their inertness.

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18
Q

What happens to the size of noble gas atoms as you move down the group?

A

The size increases

This is due to more electrons and additional electron shells.

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19
Q

What trend is observed in the boiling points of noble gases as you move down the group?

A

Boiling points increase with relative atomic mass

More electrons lead to greater forces of attraction between atoms.

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20
Q

List two uses of Helium.

A
  • Balloons
  • Cooling superconducting magnets

Helium is valued for its low density and non-reactivity.

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21
Q

What are the alkali metals?

A

Lithium, Sodium, Potassium, Rubidium, Caesium, Francium

These elements belong to Group 1 of the periodic table.

22
Q

How many electrons do alkali metals have in their outer shell?

A

1 electron

This makes them highly reactive.

23
Q

What physical characteristics do alkali metals have?

A

Soft with low density

These metals are generally easy to cut and are less dense than water.

24
Q

What type of compounds do alkali metals form?

A

Colourless compounds

These compounds often result from their reactions with non-metals.

25
Q

What happens to the atomic size of alkali metals as you go down the group?

A

The atomic radius increases

More electron shells lead to an increase in size.

26
Q

What is the trend in reactivity of alkali metals as you move down the group?

A

Reactivity increases

The outer electron becomes easier to lose due to distance from the nucleus and increased shielding.

27
Q

True or False: A cation is larger than the original atom.

A

False

A cation is smaller as it loses electrons and has one fewer electron shell.

28
Q

What do Group 1 metals form when they react with water?

A

A metal hydroxide (an alkali) and hydrogen gas

This reaction is characteristic of alkali metals.

29
Q

What happens when lithium reacts with water?

A

Floats, steadily gives off effervescence, eventually disappears

Lithium produces hydrogen gas during the reaction.

30
Q

Describe the reaction of sodium with water.

A

Floats, moves about, melts to a sphere, effervescence, eventually disappears

Sodium reacts vigorously with water, generating heat and hydrogen.

31
Q

What occurs during the reaction of potassium with water?

A

Floats, moves about, vigorous reaction, effervescence, lilac flame, eventually disappears

Potassium’s reaction is more vigorous compared to lithium and sodium.

32
Q

What do Group 1 metals form when they react with oxygen?

A

Metal oxides

The reaction is a redox process involving oxidation and reduction.

33
Q

What occurs at room temperature when Group 1 metals react with oxygen?

A

Form a white solid oxide covering the surface

This oxide can inhibit further reaction with oxygen.

34
Q

What happens when alkali metals are heated in oxygen?

A

Burn vigorously, forming oxide as a white smoke

The reaction produces metal oxides that can be hazardous.

35
Q

What are the products of Group 1 elements reacting with chlorine?

A

Chlorides, which are white solids at room temperature and dissolve in water to form colourless solutions

These reactions are highly exothermic.

36
Q

What are two characteristics of transition elements compared to normal metals?

A

Higher melting points and densities; stronger and harder

Transition metals have distinct physical properties that differentiate them from alkali and alkaline earth metals.

37
Q

How do transition metals differ in reactivity compared to normal metals?

A

Much less reactive and do not react as vigorously

This lower reactivity contributes to their use in various applications, including catalysts.

38
Q

What type of ions do transition metals form?

A

Transition metals form ions with different charges, e.g., Fe2+ and Fe3+.

39
Q

What characteristic is common to transition metals in terms of their compounds?

A

Transition metals usually form coloured compounds.

40
Q

What is an example of a catalyst used by transition metals?

A

Iron in the Haber process to make ammonia.

41
Q

What are the halogens?

A

Group 7 elements that are diatomic molecules.

42
Q

How many electrons do halogens have in their outer shell?

A

7 electrons.

43
Q

What do halogens want to do to achieve a full outer shell?

A

Gain an electron.

44
Q

What are the colours of the halogens?

A
  • Fluorine: pale-yellow gas
  • Chlorine: green gas
  • Bromine: red-brown liquid
  • Iodine: grey solid or purple vapour.
45
Q

What trend occurs in reactivity as you go down group 7?

A

They become less reactive.

46
Q

What makes it harder for halogens to gain an extra electron as you go down the group?

A

The outer shell is further from the nucleus and there is increased shielding by inner shells.

47
Q

What happens to the melting and boiling points of halogens as you go down the group?

A

They have higher melting and boiling points.

48
Q

How do the relative atomic masses of halogens change down the group?

A

They have higher relative atomic masses due to more protons.

49
Q

What type of reaction occurs when halogens react with metals?

A

A redox reaction producing salts (halides).

50
Q

What type of bonds hold halides (salts) together?

A

Ionic bonds.

51
Q

What is the result of a halogen reacting with a non-metal?

A

A covalent compound called a non-metal halide (e.g., hydrogen chloride).

52
Q

What occurs in a displacement reaction involving halogens?

A

A more reactive element takes the place of another in the salt.

Chemistry (16 decks)

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