Question

bohr model practice
directions: use the periodic table to draw a bohr model of the following atoms.
helium

of protons

of neutrons

energy levels

of electrons

valence electrons =
boron

of protons

of neutrons

energy levels

of electrons

valence electrons =
phosphorus

of protons

of neutrons

energy levels

of electrons

valence electrons =

Explanation:

Step1: Determine protons for Helium

The atomic number of Helium is 2, so number of protons = 2.

Step2: Determine neutrons for Helium

Helium - 4 isotope is common, mass number = 4, neutrons = mass number - protons = 4 - 2=2.

Step3: Determine energy levels for Helium

Helium has 1 energy level (K - level) as it has only 2 electrons.

Step4: Determine electrons for Helium

In a neutral atom, number of electrons = number of protons, so electrons = 2.

Step5: Determine valence electrons for Helium

Valence electrons are electrons in outermost shell. Helium has 2 electrons in its only shell, so valence electrons = 2.

For Boron:

Step1: Determine protons for Boron

The atomic number of Boron is 5, so number of protons = 5.

Step2: Determine neutrons for Boron

Boron - 11 is common, mass number = 11, neutrons = mass number - protons = 11 - 5 = 6.

Step3: Determine energy levels for Boron

Boron has 2 energy levels (K and L - levels) as it has 5 electrons.

Step4: Determine electrons for Boron

In a neutral atom, number of electrons = number of protons, so electrons = 5.

Step5: Determine valence electrons for Boron

Boron has 3 electrons in its outermost (L) shell, so valence electrons = 3.

For Phosphorus:

Step1: Determine protons for Phosphorus

The atomic number of Phosphorus is 15, so number of protons = 15.

Step2: Determine neutrons for Phosphorus

Phosphorus - 31 is common, mass number = 31, neutrons = mass number - protons = 31 - 15 = 16.

Step3: Determine energy levels for Phosphorus

Phosphorus has 3 energy levels (K, L and M - levels) as it has 15 electrons.

Step4: Determine electrons for Phosphorus

In a neutral atom, number of electrons = number of protons, so electrons = 15.

Step5: Determine valence electrons for Phosphorus

Phosphorus has 5 electrons in its outermost (M) shell, so valence electrons = 5.

Answer:

Atom	# of Protons	# of Neutrons	Energy Levels	# of Electrons	Valence electrons
Boron	5	6	2	5	3
Phosphorus	15	16	3	15	5