Trend in reactivity down group 2 reaction with water

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atman7
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Hi, i have a five mark question here with no mark scheme cause my teacher didnt give me one for it the final question is:

Describe and explain the trend, down the group, in the reactivity of Group 2 elements with water. (5 marks)

I got one mark for stating that as you go down the group the reactivity with water increases.


I was wondering if anyone knew what other things to write about.

Thanks
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shengoc
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(Original post by atman7)
Hi, i have a five mark question here with no mark scheme cause my teacher didnt give me one for it the final question is:

Describe and explain the trend, down the group, in the reactivity of Group 2 elements with water. (5 marks)

I got one mark for stating that as you go down the group the reactivity with water increases.

I was wondering if anyone knew what other things to write about.

Thanks
1) Write an eqn for it,
M + 2H2O -----> M(OH)2 + H2

It is metal(II) hydroxide, the 2 should be a subscript.

2) You see effervescence, due to H2 being released. You also see the solution goes cloudy-ish, ie ppt forming, solubility of the hydroxides decreases down the group as the size of cation gets bigger. The metal obviously slowly disappears as most are consumed up in the reaction.

3) Like you said, down the group, reactivity increases, because the valence electrons are less bound by the nucleus electrostatic potential, ie lower effective nuclear charge; can elaborate more on this.
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qqwertyuiop
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The lower the element is in group 2 the more reactive it is. This is because of the shielding effect, where the electron shells shield some of the attraction from the nucleus and therefore the force between the protons and electrons decreases. This is also the same for group 1 and 3 as all of them form positive ions - they loose electrons. I am a student in year 10 and am happy to help you.
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charco
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(Original post by qqwertyuiop)
The lower the element is in group 2 the more reactive it is. This is because of the shielding effect, where the electron shells shield some of the attraction from the nucleus and therefore the force between the protons and electrons decreases. This is also the same for group 1 and 3 as all of them form positive ions - they loose electrons. I am a student in year 10 and am happy to help you.
loose (adjective) = when something is not tight
lose (verb) = to not have anymore

I am an old git and am happy to help you ...
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