Elements, Compounds and Mixtures
Suggest one Safety Precaution that you must take while handling very reactive materials in a lab?
Any one of the lab saftey precautions
Why is copper used to make electric wires?
Because it conducts electricity.
What is the name of the rows of the periodic table?
Periods
Is an alloy an element, compound or mixture?
Mixure
The number of electron shells gives you what?
Period
Define a compound.
Is it where two different kinds of atoms are bonded together?
Why is copper used to make coins?
Because it does not rust.
What is the names of the columns of the periodic table?
Groups
Pure copper is very soft. So an alloy of copper and zinc called brass is used to make utensils and keys?
Can you guess a property of brass that is different from copper?
Brass is not as bendy as copper.
Brass is harder than copper.
The number of electrons in the outer shell give you what?
Group
What is the name of the element Na?
Sodium.
Why is steel used to make cooking utensils?
Because it is a good conductor of heat.
What is the name of the series of elements otherwise referred to as "Group 1 Elements"?
Alkali Metals.
Copper melts at 500 degrees centigrade.
Zinc melts as 800 degrees centigrade.
You have an alloy of copper and zinc called brass.
How would you separate the zinc from the copper?
heat it to a temperature greater than 500 degrees centigrade but less than 800 degrees centigrade
your copper will melt into a liquid but zinc will still be a solid.
Two of these electron configurations are in Period 2. What are they?
A and B
What is the suffix that you give for a compound that contains the letters CO3?
Carbonate.
Why is gold used to make jewellery?
Because it does not react with water (Sweat) and is thus safer to wear.
What is the trend in reactivity in Group 1?
What would I observe if I throw a series of Group 1 elements in water?
Reactivity increases for Group 1
You would observe increasingly vigorous bubbling to the point where elements at the bottom of group 1 catch fire in water. (because they react vigorously).
Iron undergoes rusting.
But an alloy of Iron and copper called brass does not rust.
Why is that?
Because copper does not rust.
Two of these electron configurations are in group 1? What are they?
A and C
Name the Compound CaOH.
Calcium Hydroxide.
In terms of the bonds between the atoms of metals in their solid state. Explain why there is a trend of increasing melting points across the periodic table
AS you go across the periodic table, the bonds between atoms of elements get stronger.
Thus, you need more heat energy to break the bonds.
Thus the melting point increases.
Balance _____ Na + ______H2O = _____NaOH +H2
2Na + 2H2O = 2NaOH + H2
An alloy called nicrome contains the metals nickel and chromium?
In a 100g of the alloy, it has been found that 70g is Nickel.
How much chromium is in the alloy
30 g (100-70)
One of these electron configurations is a non-metal. Which is it?
D.