Question

Task #3. Drawing the atomle structure of atoms.

1. On the following page, draw the atomic structure of the elements using the follow
Ing directions and example,
2. Use the planetary model discussed in class.
3. First, use the atomic number and mass number of the element to determine the
number of protons and neutrons of the atom.
4. Next, draw a small circle to represent the nucleus (to match the example on the
next page)
5. Inside this circle, write the number of protons and the number of neutrons that
the atom has
6. Determine the number of electrons of the atom,
7. Determine the number of shells of the atom. For simplicity, we will assume that the
first shell can hold up to 2 electrons, the second shell can hold up to 8 electrons,
and, for the main group elements used in this activity, the third shell can hold up
to 8 electrons. (Note that the transition elements can hold up to 18 electrons in
their third shell, but we will not be dealing with those elements in this activity)
8.
Draw circles around the nucleus to represent the shells.
9. Make large dots on each circle to represent the number of electrons in that shell,

Answer 1

The representation of an element includes a superior number that indicates the massic number, and an inferior number that indicates the atomic number. We need to know that every atom is identified by its number of protons and neutrons. So,

Representation ⇒ ᵃ X ₀

Where

• X is the element
• a is representing the massic number, which is defined as the sum of the number of protons and the number of neutrons.
• z is the atomic number, which is the number of protons ⇒ represented as 0 above

In electrically neutral atoms, the number of protons equals the number of electrons. This means that the atomic number also indicates the number of electrons.

We will call n to the number of neutrons, which equals a - z

When protons, neutrons, and electrons get together to form an atom, they lose part of their mass as energy. This is why the atomic weight is slightly inferior to the sum of masses.

So, what you need to know is that

• Nº of protons = Atomic number → z

• Nº of neutrons = Massic number - Atomic number → n = a - z

• Nº of Electrons = Nº of protons = Atomic number → z

When representing these atom structures using the planetary model, there must be a nucleus surrounded by orbits. In the nucleus there are protons and neutrons. In the orbits, there are electrons in different energetic levels.

• Nucleus → Protons + Neutrons → circle indicating number of P⁺ + N⁰

• Orbits → Around the nucleus → Following the energy levels

The energy levels indicate how many electrons, e⁻, maximum must be placed per level -orbit- → seven levels

1. K ⇒ 2e⁻
2. L ⇒ 8 e⁻
3. M ⇒ 18 e⁻
4. N ⇒ 32e⁻
5. O ⇒ 32e⁻
6. P ⇒ 18e⁻
7. Q ⇒ 8e⁻

So, the number of orbits drawn depends on the number of electrons.

Let us analyzetwo examples.

1) CARBON

Element representation ⇒ ¹⁴ C ₆

• Massic number = 14

• Atomic number = 6

So, from this information we can assume that

• Nº of protons = Atomic number → 6

• Nº of neutrons = Massic number - Atomic number → 14 - 6 = 8

• Nº of Electrons = Nº of protons = Atomic number → 6

Representation -Planetary model-

• Nucleus → Protons + Neutrons → 6 P⁺ + 8 N⁰

• Orbits → Electrons → 6 e⁻ → We need to draw two levels

1. K ⇒ 2e⁻
2. L ⇒ 4 e⁻

Note: In the attached files you will find the model.

1) SILICIUM

Element representation ⇒ ²⁸ Si ₁₄

• Massic number = 28

• Atomic number = 14

So, from this information we can assume that

• Nº of protons = Atomic number → 14

• Nº of neutrons = Massic number - Atomic number → 28 - 14 = 14

• Nº of Electrons = Nº of protons = Atomic number → 14

Representation -Planetary model-

• Nucleus → Protons + Neutrons → 14 P⁺ + 14 N⁰

• Orbits → Electrons → 14 e⁻ → We need to draw three levels

1. K ⇒ 2e⁻
2. L ⇒ 8 e⁻
3. M ⇒ 4 e⁻

Note: In the attached files you will find the model.