Part a add single electrons and/or electron pairs as needed to complete the electron-dot symbol for astatine, at. to return the atom to its original state, use the reset button. click to select an electron-pair or single electron, then click on the element symbol to add electrons. click the reset button to clear all electrons and start over. view available hint(s) aannn

7 valence electrons

Explanation:

Astatine has the atomic number 85. Thus, its electron configuration is:

[Xe] 4f¹⁴ 5d¹⁰ 6s² 6p⁵

As we can see, in the last level (6) it has 2 + 5 = 7 electrons, that is, astatine has 7 electrons in its valence shell. In the Lewis dot structure (attached) we write 3 pairs of electrons and 1 unpaired electron around the symbol of At.

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