In Figure 5, the letters A, E, G, J, X and Z show the positions of six elements in the periodic table - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2019 - Paper 1
Question 5
In Figure 5, the letters A, E, G, J, X and Z show the positions of six elements in the periodic table.
These letters are not the symbols of the atoms of these elemen... show full transcript
Worked Solution & Example Answer:In Figure 5, the letters A, E, G, J, X and Z show the positions of six elements in the periodic table - Edexcel - GCSE Chemistry Combined Science - Question 5 - 2019 - Paper 1
Step 1
Using the letters A, E, G, J, X and Z
(i) give the letters of the two elements that are non-metals.
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Answer
The two non-metal elements are E and G.
Step 2
Using the letters A, E, G, J, X and Z
(ii) give the letters of two elements in period 2.
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Answer
The two elements in period 2 are E and J.
Step 3
Using the letters A, E, G, J, X and Z
(iii) give the letter of an element that normally forms an ion with a charge of +1.
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Answer
The element that normally forms a +1 ion is J.
Step 4
All atoms of element E in this sample contain
(iv) A 5 protons
B 5 neutrons
C 6 protons
D 6 neutrons.
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Answer
The correct option is A; all atoms of element E contain 5 protons.
Step 5
Element X has an atomic number of 18.
State the electronic configuration of an atom of element X.
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Answer
The electronic configuration of element X is 2.8.8.
Step 6
In an experiment, 3.5 g of element A reacted with 4.0 g of element G to form a compound.
Calculate the empirical formula of this compound.
(relative atomic masses: A = 7, G = 16)
You must show your working.
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Answer
To find the empirical formula, first calculate the number of moles of each element:
Moles of A = \frac{3.5 \text{ g}}{7 \text{ g/mol}} = 0.5 ext{ moles}
Moles of G = \frac{4.0 \text{ g}}{16 \text{ g/mol}} = 0.25 ext{ moles}
Next, divide both values by the smaller number of moles:
Moles of A: \frac{0.5}{0.25} = 2
Moles of G: \frac{0.25}{0.25} = 1
The empirical formula of the compound is A₂G.
Step 7
An oxygen atom has six electrons in its outer shell.
A hydrogen atom has one electron in its outer shell.
Complete the dot and cross diagram of a molecule of water, H₂O.
Show outer shell electrons only.
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Answer
The dot and cross diagram for water should show an oxygen atom in the center with six electrons, and two hydrogen atoms, each sharing their one electron with oxygen:
H •
|
• O •
|
H •
In this diagram, the '•' represents the electrons, with shared electrons between the hydrogen and oxygen indicated.
