The ancient Greeks argued that all matter was made up of just four 'elements': earth, air, fire and water - Leaving Cert Chemistry - Question 5 - 2017
Question 5
The ancient Greeks argued that all matter was made up of just four 'elements': earth, air, fire and water. We now know that there are over 100 elements that are list... show full transcript
Worked Solution & Example Answer:The ancient Greeks argued that all matter was made up of just four 'elements': earth, air, fire and water - Leaving Cert Chemistry - Question 5 - 2017
Step 1
What is the modern definition of an element?
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Answer
An element is defined as a substance that cannot be made simpler by chemical means. It is a fundamental substance that consists of atoms with the same number of protons in their nucleus.
Step 2
Name the Russian chemist, shown above, who around 1869, drew up the first successful periodic table of the elements.
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Answer
The Russian chemist is Dmitri Mendeleev.
Step 3
Define atomic number.
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The atomic number is defined as the number of protons in the nucleus of an atom. It serves as a unique identifier for each element.
Step 4
In terms of subatomic particles, how do $^{12}X$ and $^{14}X$ differ?
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Answer
The isotopes 12X and 14X differ in the number of neutrons they contain. Specifically, 12X has 6 neutrons, while 14X has 8 neutrons.
Step 5
What term is used to refer to these different forms of the same element?
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Answer
These different forms of the same element are referred to as isotopes.
Step 6
How many electrons are present in each of these atoms?
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Answer
Both 12X and 14X have the same number of electrons as protons in a neutral atom, which is 6 electrons.
Step 7
Draw diagrams to show the arrangement of electrons in the main energy levels in a neon atom.
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Answer
Neon has a total of 10 electrons arranged in two energy levels: the first energy level contains 2 electrons, while the second energy level contains 8 electrons. The diagram would depict two circles, with two dots in the inner circle and eight dots in the outer circle to represent the electron arrangement.
Step 8
Draw diagrams to show the arrangement of electrons in the main energy levels in a fluorine atom.
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Fluorine has 9 electrons arranged in two energy levels: the first energy level contains 2 electrons, and the second energy level contains 7 electrons. The diagram would show two circles, with two dots in the inner circle and seven dots in the outer circle to illustrate the electron arrangement.
Step 9
Explain which of these two elements is the more chemically reactive.
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Answer
Fluorine is more reactive than neon because fluorine has 7 electrons in its outer shell, which makes it eager to gain one more electron to achieve a stable electronic configuration. In contrast, neon has a full outer shell with 8 electrons, making it chemically inert.
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