2 - Group 2, the alkaline earth metals Flashcards

1
Q

In order, what are the group 2 elements?

A

Be, Mg, Ca, Sr, Ba, Ra

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2
Q

Are group 2 metals oxidised or reduced?

A

Oxidised as they lose electrons when they react

Oxidation state 0 → +2

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3
Q

What is the general trend in atomic radius down group 2?

A

Atomic radius increases

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4
Q

Why does atomic radius increase down group 2?

A

Down the group, the atoms have more shells of electrons making the atom bigger

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5
Q

What is the general trend in 1st ionisation energy down group 2?

A

1st IE decreases down group 2

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6
Q

Why do 1st ionisation energies decrease down group 2?

A
  • Weaker forces of attraction between nucleus and outermost electrons
  • Shielding increases
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7
Q

What is the general trend in melting points down group 2?

A

Melting point decreases

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8
Q

Why do melting points decrease down group 2?

A
  • Metallic bonding weakens as atomic size increases
  • Distance between positive ions and delocalised electrons increases so electrostatic forces between them weaken
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9
Q

Why does Mg have a lower melting point than Ca?

A

Mg’s crystal structure changes

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10
Q

What is the trend in reactivity down group 2?

A

Reactivity increases

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11
Q

Going down the group, why are group 2 elements more reactive?

A

Outer electrons are easier to lose
- Due to increase in atomic radii and shielding

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12
Q

When group 2 elements are reacted with oxygen, what is formed?

A

Metal oxides

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13
Q

When group 2 elements are reacted with water, what is formed?

A

Metal hydroxide & hydrogen

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14
Q

Describe the reaction of group 2 elements with water

A
  • Group 2 metals react with water in a redox reaction
  • Metals oxidise 2+
  • Metal hydroxides forms as an alkaline solution
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15
Q

What is the general equation for when group 2 elements react with water?

A

Metal + water → metal hydroxide + hydrogen

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16
Q

When magnesium is reacted with steam, what happens and what is produced?

A

Magnesium oxide - MgO
- Mg reacts vigourously and burns with a bright white flame
- MgO produced appears as a white powder

17
Q

When magnesium is reacted with warm water, what is produced?

A

Magnesium hydroxide - Mg(OH)2
- A much slower reaction than with steam
- No flame produced

18
Q

Be doesn’t react in water, Mg reacts with steam or warm water, what do the other group 2 metals react with?

A

Cold water to form hydroxides

19
Q

What would be observed when group 2 metals react with water?

A
  • Fizzing, more vigorous down group
  • Metal dissolving, faster down group
  • The solution heating up, hotter down group
  • With Ca a white precipitate appears, less precipitate down group