Atoms and Electron Dots

Lewis Electron Dot Structure

Mrs. Perlita V. Sanchez

Grade 9 Science

I. OBJECTIVES

• Illustrate Lewis Electron Dot Structure of some elements.

• Understand the Octet Rule

• Identify which element or atom will more likely give or accept electrons

Lewis Electron Dot Structure

• Proposed by Gilbert Lewis

• A model used to illustrate the electrons in the outermost energy level of an atom

• It helps picture out the Octet Rule and how chemical bonding takes place between elements

Lewis Electron Dot Structure

The chemical symbol of an element is surrounded by a number of dots which are the valence electrons.

Multiple Choice

The outermost electrons of an atom are __________.

• outermost electron

• Lewis electrons

• valence electrons

• octet electrons

Octet Rule or Rule of Eight

• Elements with with complete number of electron are those with 8 valence electrons and they are described as STABLE ELEMENTS

• Example: ₁₈Ar 2) 8) 8) valence electron is 8 therefore ₁₈Ar is stable.

• Elements with incomplete number of valence electrons are those with less than 8 valence electrons and they are described as UNSTABLE ELEMENTS

• Example: ₁₁Na 2) 8) 1) valence electron is 1, its is less than 8 therefore ₁₁Na is unstable.

Octet Rule Exemption

The element Helium (₂He) is exemption to this rule. Since helium has 2 electrons, its energy level is complete with 2 valence electrons making it a stable element.

Multiple Choice

Identify if this element ₁₉K 2) 8) 8) 1) is stable or unstable?

• Stable

• Unstable

Multiple Choice

Identify if the element ₁₀Ne 2) 8) is stable or unstable?

• Stable

• Unstable

Multiple Choice

How many valence electrons should an element have for it to be considered as a STABLE element?

• 2

• 10

• 6

• 8

Accept, Lose or Share?

• Elements with fewer electrons tend to lose electrons rather than keeping them because in this way they can achieve a stable condition.

• On the other hand, elements with more valence electrons will ten to accept electrons from other elements because they only need fewer electrons to complete their valence electrons.

• In the case of carbon atom with 4 valence electrons, it will either lose or accept electron but it will enter into sharing of electrons.

Stable Elements

• Stable elements DOES NOT accept, lose or share electron because their valence shell is already complete.

Multiple Choice

Which of the elements will share electrons?

• ₁₂Mg 2) 8) 2)

• ₁₄Si 2) 8) 4)

• ₁₇Cl 2) 8) 7)

• ₁₅P 2) 8) 5)

Multiple Choice

Which element will most likely lose its electrons?

• Na 2)8)1)

• N 2)5)

• O 2) 6)

• F 2)7)

Multiple Choice

Which element will prefer to accept electrons from another element?

• ₁₁Na 2) 8) 1)

• ₂₀Ca 2) 8) 2)

• ₁₆S 2) 8) 6)

• ₁₀Ne 2) 8)

Key Concepts

• Stability of an element can be identified by knowing how many electrons can be found in its outermost energy level.

• The Octet Rule or Rule of Eight, states that for an element to become stable it should have eight valence electrons in its outermost energy level; if not then, it is unstable. With the exemption of Helium.

• The Lewis Electron Dot Structure is used to show the valence electron of an element or atom helps us visualize the Octet Rule.