Group II (Alkaline Earth Metals)

Question 1

Metallic Bonding (definition)

Answer 1

is a type of chemical bonding that rises from electrostatic attractive force between conduction electrons (in the form of an electron sea of delocalized electrons) and positively charged metal ions.

A metallic bond is produced when electron orbitals overlap and all electrons are shared between atoms - this is referred as a “sea of electrons”

Question 2

physical properties of metals (9)

Answer 2

They have a luster ‘shiny’ appearance
They conduct heat and electricity
They can be drawn into wire (are ductile)
They can be hammered into thin sheets (are malleable)
They make a ‘clanging’ sound when you hit them (are sonorous)

1) lustrous 2) good conductors 3) high melting point 4) high density 5) malleable 6) ductile (can be drawn into wires) 7) usually solid at room temp 8) opaque as a thin sheet 9) sonorous

Question 3

Atomic

Question 4

Flame test; Be and Mg

Answer 4

beryllium and magnesium elements don’t exhibit any color to flame. The electrons in Be and Mg are too strongly bound to get excited by flame.

Question 5

Magnesium (group II)

Answer 5

Mg is one of the most plentiful elements found in the Earth’s crust and

is a key component in chlorophyll, the substance in green plants used in photosynthesis.

Magnesium is useful in healthcare as it is one of the main ingredients in antacids, laxative and Epsom salts.

Combustion of magnesium yields a bright white, long lasting flame, making it useful in fireworks and flares

Question 6

Calcium (group II)

Answer 6

Calcium is even more plentiful on Earth than Magnesium. The silvery, semi-soft metal easily forms compounds with both oxygen molecules and water. In nature it is typically found as calcium carbonate, or limestone. Calcium is a key component in the structures of living things including bones, teeth, shells and exoskeletons. Calcium is also an important substance for manmade structures because it is used to make plaster, cement, drywall and other building materials.

Question 7

Strontium (Group II)

Answer 7

Salts derived from strontium compounds burn red and are used in fireworks and signal flares

Question 8

Barium (Group II)

Answer 8

X-rays can not penetrate Ba. Barium sulphate is commonly used to aid in using x-rays to detect problems in the digestive tract. This compound is insoluble in water and coats the oesophagus, stomach and intestines when swallowed. Barium nitrate and Barium chlorate are used in fireworks to give off green light when heated

Question 9

solubility of Sulphates/carbonates/hydroxides

Mg Ca Sr Ba
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Answer 9

순서대로
sulphates soluble»>insoluble
carbonates insoluble&raquo_space;> more
hydroxides insoluble»»soluble