Methane has the formula, CH4.
Look at the representations of methane.
Describe the limitations of a displayed formula.
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Methane has the formula, CH4.
Look at the representations of methane.
Describe the limitations of a displayed formula.
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This question is about structure and bonding.
Look at the two structures, A and B, in Fig. 22.1.
[2]
[2]
[1]
Look at the structure of a metal in Fig. 22.2. Metals are malleable, which means they can be hammered or pressed into shape without breaking or cracking.
Explain why metals are malleable.
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Dmitri Mendeleev produced a Periodic Table of elements which is the basis for our modern Periodic Table. He left gaps for elements that had not been discovered yet as shown in Fig. 23.1.
Describe two ways Mendeleev arranged the elements in his Periodic Table.
Describe how the elements are arranged in the modern Periodic Table.
Mendeleev left gaps in his Periodic Table for undiscovered elements. He predicted properties of these elements.
Table 23.1 shows the predicted properties for one of these elements in one of the gaps.
Mendeleev called this element ‘eka-silicon’.
Appearance | Grey metal |
Melting point (°C) | Over 800 |
Relative atomic mass | 72 |
Density (g / cm3) | 5.5 |
Table 23.1
Table 23.2 shows some of the elements that were discovered after Mendeleev published his Periodic Table.
Scandium (Sc) | Gallium (Ga) | Germanium (Ge) | Technetium (Tc) | |
Appearance | Silver-white metal | Silver-blue metal | Grey-white metal | Grey metal |
Melting point (°C) | 1541 | 30 | 947 | 2157 |
Relative atomic mass | 45.0 | 69.7 | 72.6 | 98.0 |
Density (g / cm3) | 3.0 | 5.9 | 5.35 | 11.0 |
Table 23.2
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Mendeleev did not predict the existence of argon, neon, krypton or xenon.
The electron arrangement of argon is 2,8,8.
What does this tell you about the reactivity of argon?
Explain your answer.
[2]
Proton | ||
Neutron | ||
Electron |
Table 23.3
[3]
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Look at the diagram.
It shows part of Mendeleev’s Periodic Table which was developed in 1871.
Mendeleev arranged the elements in order of relative atomic mass.
Group | 1 | 2 | 3 | 4 | 5 | 6 | 7 | |
Periods | ||||||||
1 | H 1.008 |
|||||||
2 | Li 6.939 |
Be 9.012 |
B 10.81 |
C 12.011 |
N 14.007 |
O 15.999 |
F 18.998 |
|
3 | Na 22.99 |
Mg 24.31 |
Al 29.98 |
Si 28.09 |
P 30.974 |
S 32.06 |
Cl 35.453 |
|
4 | K 39.102 |
Ca 40.08 |
As 74.92 |
Se 78.96 |
Br 79.909 |
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5 | Rb 85.47 |
Sr 87.62 |
In 114.82 |
Sn 118.69 |
Sb 121.75 |
Te 127.60 |
I 126.90 |
|
6 | Cs 132.90 |
Ba 137.84 |
Tl 204.37 |
Pb 207.19 |
Bi 208.98 |
Describe the differences between Mendeleev’s Periodic Table and the modern-day version.
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Metal elements and non-metal elements have different physical properties.
The table shows the physical properties of some elements.
Element | Melting point (°C) | Density (g/cm3) | Electrical conductivity | Thermal conductivity | Cost |
A | high | high | good | good | high |
B | low | low | good | poor | high |
C | high | low | good | good | low |
D | high | high | poor | poor | low |
A
B
C
D
Explain your answer.
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[1]
Element C burns in oxygen to make white clouds of its oxide.
Describe how you could test the oxide to find out if the element is a metal.
Isotope | Number of protons |
Number of neutrons |
Number of electrons |
Chlorine-35 | ............................... | ............................... | ............................... |
Chlorine-37 | ............................... | ............................... | ............................... |
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