Answer:
all of them have seven valence electron
Answer is: beryllium-10.
The diagram shows that atom has 4 protons, 5 neutrons and 2 valence electrons.
Atomic number is the number of protons, which is characteristic of a chemical element, beryllium (Be) is an element with atomic number 4.
Two valence electrons means that atom is from 2. group of periodic table, only beryllium is from that group; sodium (1. group), boron (13. group) and carbon (14. group).
Beryllium-10 has 6 neutrons, so it is isotope (different number of neutrons or mass number).
Answer: 25g/ml
Explanation:
Density = 100.0g/ 4.0mL = 25g/mL
<span>Rule of the octet is used in chemistry to indicate the tendencies of the atoms when they complete the energy level to obtain stability. Covalent bonds are what occurs when two atoms join and reach the stable octet. They are related because through this union electrons are shared and the covalent bond is produced and the rule of the octet is given to show the tendency of this union.</span>