QQuestionChemistry
QuestionChemistry
How many valence electrons does lithium, with atomic number 3, have in its outer shell?
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Answer
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Step 1:: Recall the definition of valence electrons
Valence electrons are the outermost electrons in an atom and are involved in the formation of chemical bonds with other atoms.
Step 2:: Understand how to find valence electrons using an atom's atomic number
The number of valence electrons in an atom can be found by looking at its position in the periodic table or by using its atomic number, which is the number of protons in the atom's nucleus. The atomic number for lithium is 3.
Step 3:: Use the atom's atomic number to determine the number of valence electrons
n = \text{floor}(1 + \sqrt{3}) = 2
The highest occupied energy level (or principal quantum number, n) for an atom is given by the formula n = floor(1 + sqrt(atomic number)), where floor() is the greatest integer function. For lithium, we have:
Step 4:: Determine the number of valence electrons
2\ \text{electrons in the second shell} = (2 \times 2) - 1\ (\text{since one electron is already in the first shell})
For a neutral atom, the number of valence electrons is equal to the difference between the atomic number and the total number of electrons in the inner shells. For lithium, the first shell can hold up to 2 electrons (following the pattern of 2n^2 where n is the principal quantum number). Since lithium has 3 protons, it has gained 1 electron in its 1s shell, filling it up. Therefore, lithium's outermost shell (the second shell) has:
Step 5::
Final Answer
Lithium has 1 valence electron in its outermost shell.
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