In a sample of potassium atoms, 90 were found to be potassium-39, and 10 were potassium-40. Calculate the relative atomic mass of potassium.
(90x39)+(10x40) / 100 = 39.1
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Describe how potassium-39 is different from potassium-40.
Potassium-40 has one more neutron.
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What is an 'isotope'?
An atom of the same element with a different mass.
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Scientists wanted to date some archaeological remains made of wood. Describe how they could use carbon-14 to find the age of the wood.
Measure the carbon-14 present in the sample, compare it with how much should be present today/use half-life of carbon-14 to find out how old the specimen is.
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What does (aq) mean?
A water solution.
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Calculate the relative formula mass (Mr) of barium chloride (Relative atomic masses: Ba=137, Cl=35.5)
137+35.5 = 172.5
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Draw electronic diagrams for calcium.
2 on the first ring, 8 on the second ring, 8 on the third ring and 2 on the fourth ring.
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How many outer electrons does bromine and strontium have?
7 and 2.
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Why is it important to know the number of outer electrons?
It gives an indication of the elements reactivity.
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Noble gases are very unreactive elements. Explain why in terms of electronic structure.
They have no electrons on their outer shell.
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What are the melting and boiling points of potassium fluoride and in what form does it conduct electricity?
Boiling point- 1502 degrees celcius, melting point- 857 degrees celcius. It conducts electricity as a solution.
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Describe the electronic structure of a potassium ion and a fluoride ion.
Potassium becomes a positive ion (2,8,8), and fluoride would become a negative ion (2,8)
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Explain how two ions form the compound potassium fluoride.
The potassium loses its outer electron to the fluorine ion, making 2 ions. The oppositely charged ions the attract each other.
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Explain why solid sodium chloride does not conduct electricity but when dissolved in water it does.
Because the electrons are not free to move, but when in a solution, it can conduct electricity.
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A student took some molten sodium chloride and tested it for electrical conductivity. It was a conductor. Explain why molten sodium chloride can conduct electricity.
The ions are also free to move in sodium chloride molten.
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Write a word equation for the reaction of sodium with water.
Sodium + water ---> sodium hydroxide + hydrogen.
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Explain why all group 1 metals form positive ions with a 1+ charge.
Because the outer ring of the atom will have less energy.
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How would caesium would react with water? Explain your answer.
Caesium explodes on contact with water, potassium bursts into flames.
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How are potassium and sodium extracted from their metal ores?
By using electrolysis.
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Draw a diagram to show electron arrangement of a chloride ion.
2 on the first ring, 8 on the second ring, and 7 on the outer ring but one added to create the ion.
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What is the charge of a chloride ion?
1-
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Name the element with the same electronic structure as a chloride ion.
Argon
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Other cards in this set
Card 2
Front
Describe how potassium-39 is different from potassium-40.
Back
Potassium-40 has one more neutron.
Card 3
Front
What is an 'isotope'?
Back
Card 4
Front
Scientists wanted to date some archaeological remains made of wood. Describe how they could use carbon-14 to find the age of the wood.
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