Question

beryllium - be is in group number... *
group 2
group 3
group 4
group 7
an element with a mass number of 11 and an atomic number of 5 has how many neutrons? *
11
5
6
16
what is the name of the group that never reacts with other elements and have 8 valence electrons? *
noble gases
transition metals
halogens
borons

Explanation:

First question:

Step1: Recall the periodic table group of Beryllium

Beryllium (Be) has an atomic number of 4. In the periodic table, elements are arranged in groups. Beryllium is in Group 2.

Second question:

Step1: Use the formula for neutrons

The formula for the number of neutrons \(N\) is \(N=\text{Mass number}-\text{Atomic number}\). Given mass number \(A = 11\) and atomic number \(Z=5\).
\(N=11 - 5\)

Step2: Calculate the value

\(N = 6\)

Third question:

Step1: Recall the properties of different groups

• Noble gases: Have 8 valence electrons (except helium which has 2) and are inert (do not react easily).
• Transition metals: Have variable valence electrons and can form various compounds.
• Halogens: Have 7 valence electrons and are reactive.
• Borons: Not a standard group name for a group with 8 valence electrons.

Answer:

1. Group 2
2. 6
3. Noble gases