Multiple Choice
On the periodic table, gold has the atomic number 79. This means that:
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2. Atoms & Elements
Periodic Table: Element Symbols
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3. Sodium (Na) is found in which period of the periodic table?
A
Period 1
B
Period 2
C
Period 3
D
Period 3
Verified step by step guidance1
Recall that the periodic table is organized into periods (rows) and groups (columns), where each period corresponds to the principal energy level (n) being filled with electrons.
Identify the atomic number of sodium (Na), which is 11, meaning it has 11 electrons.
Determine the electron configuration of sodium: \$1s^2 2s^2 2p^6 3s^1$.
Note that the highest principal quantum number (n) in sodium's electron configuration is 3, indicating that its valence electron is in the third energy level.
Conclude that sodium is located in Period 3 of the periodic table because the period number corresponds to the highest occupied principal energy level.
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