[redXI]

1. Choose from the elements: sodium, oxygen, potassium, carbon, magnesium and chlorine...
a. two elements that exist naturally as diatomic molecules?
b. element with highest melting point?
c. one pair that does not form a compound with each other?
2. Three elements P, Q , and R have proton numbers between 2 and 10. Atom P has one electron more than a noble gas structure and atom Q has three electrons more than a noble gas structure. Atom R, however, has two electrons fewer than a noble gas structure.
a. Which element is most likely to be an ion carrying +1 charge and -2 charge?
b. What would be the formula for the simplest compound formed from a. P and R , b. Q  and R?
c. What type of bonding exists between, a. Atom Q and R? b. Two atoms of R?
d. Which of these elements are metals and which non-metals?

[Donaldson Tan]

forum policy requires you to show you have attempted the problem.

Q(1) is a very textbook-like question. Have your read your notes?

Q(2) requires you to fit your unknown elements into the periodic table, based on the given description.

[redXI]

I solved that ones. and the next, Is this correct?

Choose from the elements: sodium, oxygen, potassium, carbon, magnesium and chlorine...
a. one pair that forms a covalent compound
b. four pairs that form ionic compounds
c. two gaseous elements

answers:

a. CO2
b. Na2O, K2O, MgO, NaCl
c. O, C

[JZ_1]

I dunno about the other ones...they seem correct
but for (c)…Carbon isnt a gas at room temp....or so i dont think it is...check your answer for (C)

remember ionic compounds forms from a metal and a non-metal

most likely from group 1 and 2 combining with groups 6 or 7

[xiankai]

c) is monoatomic oxygen a gas? elemental carbon is not a gas, but its compounds can be.

[JZ_1]

I think so...well...i'm just looking at the periodic table of elements

[Donaldson Tan]

the answer for 1(c) would be any two metals. the metals won't react with each other. combining them forms a mixture known as alloy.

regarding question 2, the elements involved are He and period 2.

Atom P has 1 more electron than a noble gas configuration, so P must be in Group 1.
Atom Q has 3 electrons more than a noble gas structure, so Q must be in Group III.
Atom R has two electrons fewer than a noble gas structure. so R must be in Group VI.

can you identify the elements P,Q,R now?

[JZ_1]

It should be fairly simple, since those in groups closest to the noble gasses tend to complete their shells..according to the octet rule, having 8 electrons on theis outer shell makes them stable..and that's why the elements tend to gain or lose an electron (most likely through ionic bonds) to get that eight electrons

He....doesnt need 8 electrons...it is the exception...it has 2 electrons on itz outer shell ..and yet it is stable ( itz in the same group as the nobel gasses)

groups 1 and 2 tend to lose their electrons and groups 6 and 7 tend to gain electrons to reach that octet rule....

NOTE: you dont see any pure elements from groups 1
        or 2 in nature...the ones that are found are already
        combines with some other elements when
        they are found.