Multiple Choice
How many valence electrons does a fluorine (F) atom have?
4
views
10. Periodic Properties of the Elements
Valence Electrons of Elements
Struggling with General Chemistry?
Join thousands of students who trust us to help them ace their exams!Watch the first videoMultiple Choice
Which of the following pairs of elements have their valence electrons in the same shell?
A
Li and Ne
B
K and Ca
C
C and O
D
Na and Mg
Verified step by step guidance1
Recall that the valence electrons of an element are the electrons in its outermost electron shell (energy level). Elements in the same period (row) of the periodic table have their valence electrons in the same principal energy level (shell).
Identify the principal energy level (shell number) for each element by looking at their period number in the periodic table. For example, elements in period 2 have valence electrons in the second shell (n=2), period 3 elements have valence electrons in the third shell (n=3), and so on.
Check each pair of elements given in the problem and determine if both elements belong to the same period, which means their valence electrons are in the same shell:
- Li (period 2) and Ne (period 2)
- K (period 4) and Ca (period 4)
- C (period 2) and O (period 2)
- Na (period 3) and Mg (period 3)
Compare the periods of each pair. If both elements are in the same period, their valence electrons are in the same shell. If they are in different periods, their valence electrons are in different shells.
Conclude that the pair Na and Mg both have valence electrons in the third shell (n=3), which is why they have their valence electrons in the same shell.
2:32mWatch next
Master Main Group Elements Valence Electrons with a bite sized video explanation from Jules
Start learningRelated Videos
Related Practice
Valence Electrons of Elements practice set
Problem sets built by lead tutorsExpert video explanations