Leaving Cert Chemistry Electron Arrangement: 4. Answer eight of the following

4. Answer eight of the following (a), (b), (c), etc - Leaving Cert Chemistry - Question 4 - 2015

Question 4

4. Answer eight of the following (a), (b), (c), etc. (a) How many (i) electrons, (ii) neutrons does a $ ext{Se}^{2-}$ ion have? (b) Define an atomic orbital. (c) ... show full transcript

Worked Solution & Example Answer:4. Answer eight of the following (a), (b), (c), etc - Leaving Cert Chemistry - Question 4 - 2015

Step 1

How many (i) electrons, (ii) neutrons does a $ ext{Se}^{2-}$ ion have?

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Answer

To determine the number of electrons and neutrons in the $ext{Se}^{2-}$ ion:

Electrons: A neutral selenium (Se) atom has an atomic number of 34, meaning it has 34 protons and, therefore, 34 electrons. Since the ion is $ext{Se}^{2-}$ , it has gained 2 additional electrons, resulting in a total of: $34 + 2 = 36\text{ electrons}.$
Neutrons: The isotope of selenium represented typically weighs about 78 (the most stable isotope is $ext{Se}^{78}$ ). The number of neutrons is determined by: $\text{Neutrons} = \text{mass number} - \text{atomic number} = 78 - 34 = 44\text{ neutrons}.$

Step 2

Define an atomic orbital.

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Answer

An atomic orbital is defined as the region in space around the nucleus of an atom where there is a high probability of finding an electron. This concept illustrates areas where electrons are likely to be located, characterized by specific shapes and energy levels.

Step 3

Write the s, p, d electron configuration for a nickel atom in the ground state.

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Answer

The electron configuration for a nickel atom (with an atomic number of 28) in its ground state is written as:

$1s^2 2s^2 2p^6 3s^2 3p^6 3d^8 4s^2$

Alternatively, in shorthand notation using the nearest noble gas, it can be expressed as:

$[Ar] 3d^8 4s^2$

4. Answer eight of the following (a), (b), (c), etc - Leaving Cert Chemistry - Question 4 - 2015

Worked Solution & Example Answer:4. Answer eight of the following (a), (b), (c), etc - Leaving Cert Chemistry - Question 4 - 2015

How many (i) electrons, (ii) neutrons does a $ ext{Se}^{2-}$ ion have?

Define an atomic orbital.

Write the s, p, d electron configuration for a nickel atom in the ground state.

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