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SOCIAL CONSTRUCTIVISM - Coggle Diagram
SOCIAL CONSTRUCTIVISM
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application
Beryllium
- x-ray windows
- as alloy
- as a moderator
Magnesium
- used in flash photography
- a reducing agent
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trend in melting point
The melting point of metals decreases down the group
- Each atoms contribute two electrons to the delocalised cloud metallic bonding gets weaker due to the increased size of ion
*Large ions mean that the electron cloud doesn’t bind them as strongly
- Group 1 metals have lower melting point that the Group 2 metal because each metal only contributes one electron to the cloud
*Magnesium doesn’t fit the trend because crystalline structure can also affect the melting point of a metal
trend in reactivity
The reactivity of alkali metals increases down the group
- the size of the element’s atoms, and the number of full electron shells, increases down the group
- down the group, the electron in the outer shell gets further away from the nucleus and is shielded by more electron shells
- the further away an electron is from the positive attraction of the nucleus, the easier it can be lost in reactions
- thus, reactivity increases with the size of the atom.
general properties
Ca, Sr and Ba
halide of metals - give colour when heated in flame due to low energy of the electron valence
-easily ionised/excited in Bunsen flame
Ca2+ : brick-red
Sr2+ : red
Ba2+ : yellowish-green
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- soft water: Water which contain the only cation (positively charged ion) Na+
- hard water: Water which contain an appreciable quantity of dissolved minerals such as Mg2+ and Ca2+ ions
water softening
- add lime water
- ion exchange
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