QQuestionChemistry
QuestionChemistry
"How many valence electrons are in an atom of strontium (Sr)? Consult the periodic table.
A. 5
B. 2
C. 47.90
D. 22"
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Answer
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Step 1:: Consult the periodic table to find the atomic number of strontium (Sr).
The atomic number of an element is the number of protons in the nucleus of an atom of that element. It also equals the number of electrons in a neutral atom of that element. Strontium is the 38th element in the periodic table, so its atomic number is 38.
Step 2:: Understand the concept of valence electrons.
Valence electrons are the outermost electrons in an atom and are involved in the formation of chemical bonds with other atoms. In other words, they are the electrons in the outermost energy level (highest principal quantum number) of an atom.
Step 3:: Determine the number of valence electrons in a strontium atom.
For main group elements (Groups 1, 2, and 13 - 18), the number of valence electrons is equal to the element's group number. Strontium is in Group 2 of the periodic table, so it has 2 valence electrons.
Final Answer
An atom of strontium (Sr) has 2 valence electrons.
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