C4 Question set 2. Flashcards
Arsenic can be used to treat some cancers.
Ben wants to analyse a mineral to see if it contain arsenic.
He looks at a table of flame colours for some elements.
arsenic blue
barium green
calcium red
copper blue
potassium purple
sodium yellow
Ben says: I can use these flame colours to show that there is no calcium or sodium in the mineral. The flame colour will not prove that the mineral contains arsenic.
Explain why what Ben says is true. [3]
If the colour does not show then the element is missing;
If the flame is blue then there may be arsenic;
copper also shows blue
other elements not included in this table may have similar colours.
Ben finds an image of the line spectrum of arsenic.
Ben says: I will take a line spectrum from the mineral. I expect it to show that the mineral contains arsenic and other elements.
How can Ben use a line spectrum to show that the mineral contains arsenic and other elements? [2]
It the mineral contain arsenic then all the spectrum lines for arsenic will be present.
There will also be additional lines caused by the other elements.
Rubidium is an element in group 1.
Find rubidium in the periodic table.
a. Which of the following statements about rubidium are true and which are false?
Rubidium is more reactive than sodium.
Rubidium is a non-metal.
Rubidium has a lower proton number than sodium.
Rubidium reacts with water to make hydrogen gas. [2]
Rubidium is more reactive than sodium. TRUE
Rubidium is a non-metal. FALSE
Rubidium has a lower proton number than sodium. FALSE
Rubidium reacts with water to make hydrogen gas. TRUE
The formula of lithium hydroxide is LiOH.
What is the formula for rubidium hydroxide?
RbOH
The table below shows the number of protons and electrons in five particles, A, B, C, D and E
protons electrons
A 3 3
B 9 9
C 3 2
D 8 10
E 17 17
(i) Which two particles are atoms from Group 7 of the periodic table?
B, E
The table below shows the number of protons and electrons in five particles, A, B, C, D and E
protons electrons
A 3 3
B 9 9
C 3 2
D 8 10
E 17 17
(ii) Which two particles are an atom and an ion of the same element? [1]
A and C
The table below shows the number of protons and electrons in five particles, A, B, C, D and E
protons electrons
A 3 3
B 9 9
C 3 2
D 8 10
E 17 17
(iii) Which particle is a negative ion? [1]
D
The table below shows the number of protons and electrons in five particles, A, B, C, D and E
protons electrons
A 3 3
B 9 9
C 3 2
D 8 10
E 17 17
Particle C is an ion. What is the overall charge on particle C?
+1
Alex plans to write an article about flame colours for a school science magazine.
He researches the flame colours of some compounds of metals from group 1 in the Periodic Table.
He talks about his findings with other students in an internet chat room.
Alex: Hi everyone. Have any of you done any research into flame test colours for group 1? I have found out that potassium and rubidium both give purple flames. I think that each group has its own flame colour.
Bea: I’ve checked out your research and agree about flame colours for potassium and rubidium. I just looked up caesium and that is purple too!
Carl: I have tested some group 2 elements, none of them were purple. They were all different colours.
Dan: Sodium is in group 1 and gives a yellow flame.
Elly. I have looked on the internet and I can’t find any elements that give a purple colour except the ones in group 1.
Fay: Lithium doesn’t have a purple flame.
Alex’s ideas are that in flame tests:
all the elements in a group have the same flame colour
each group has its own flame colour.
Explain how each piece of evidence in the chat supports or does not support Alex’s ideas.
The quality of written communication will be assessed in your answer. [6]
Points that support Alex:
2 people agree that flame colours for K and Rb are purple. Bea also finds Cs purple, and that is also in group 1.
Group 2 don’t give purple flames. (Carl)
No other elements except group 1 have purple flames (Elly)
Points that disagree with Alex:
Na gives a yellow flame, not purple, and Na is in group 1. (Dan)
Lithium does not give a purple flame (Fay) Lithium is group 1.
Elements in group 2 all have different coloured flames (Carl)
X Y Z are three elements in the Periodic Table.
X Y Z
atomic number <12 12 >12
melting point C 1278 649 839
density g/cm3 1.85 1.74 1.54
reaction with H2O none slow rapid
formula of chloride XCl2 YCl2 ZCl2
formula of oxide XO YO ZO
melting point oxide 2550 2852 2554
Jo thinks that X Y and Z are in the same group.
Ann thinks that they are not.
Who is right? Use evidence from the table to support your answer.
The quality of written communication will be assessed in your answer. [6]
Jo correct:
All are group 2, going by formula of chlorides/oxides.
Reactivity and density show a trend.
Ann correct:
melting points and boiling points do not show a trend.
