Question

Which element has six
valence electrons?
(1 point)
carbon (C)
phosphorus (P)
oxygen (O)
lead (Pb)

Answer 1

Which of the following defines
the atomic number of an
atom? (1 point)
the number of valence
electrons
the number of neutrons
the number of protons
the number of
electrons, protons, and
neutrons

Answer 2

Potassium’s atomic number is
19, and its atomic mass is
approximately 39. How many
neutrons does potassium
have? (1 point)
58
20
39
19

Answer 3

Which element does not have
the same number of electrons
in its outermost shell as the
other elements in its group?
(1 point)
boron (B)
bromine (Br)
helium (He)
hydrogen (H)

Answer 4

The element that has six valence electrons is **oxygen (O)**. Oxygen is in group 16 of the periodic table, which is known for elements that typically have six valence electrons.

Answer 5

The atomic number of an atom is defined as **the number of protons**. The atomic number uniquely identifies an element and determines its position on the periodic table.

Answer 6

To find the number of neutrons in potassium, you can use the following formula:

\[
\text{Number of neutrons} = \text{Atomic mass} - \text{Atomic number}
\]

For potassium:
- Atomic mass ≈ 39
- Atomic number = 19

Calculating the number of neutrons:

\[
\text{Number of neutrons} = 39 - 19 = 20
\]

Therefore, potassium has **20 neutrons**.

Answer 7

The element that does not have the same number of electrons in its outermost shell as the other elements in its group is **helium (He)**.

- Helium has 2 electrons in its outermost shell, while other elements in Group 18 (the noble gases) typically have 8 valence electrons (except for helium, which is an exception).
- Hydrogen (H) is in Group 1 but has only 1 electron in its outermost shell, whereas other elements in Group 1 have more than one.

However, the most consistent answer in relation to group behavior is helium, as it has a full outer shell of 2 electrons, unlike the others which fit into broader trends in their respective groups.