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Valence Electrons — Reading Comprehension

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MS-PS1-1

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This middle school science passage introduces students to the concept of valence electrons, the outermost electrons that control how atoms interact and combine. Aligned with NGSS MS-PS1-1, it explains how the number of valence electrons can be determined by an element’s group on the periodic table, and how this affects chemical stability and bonding. Through clear explanations and real-world examples like sodium, oxygen, and neon, students explore how valence electrons drive the formation of molecules and influence the behavior of different elements. The passage integrates academic vocabulary, relevant context, and connects to broader scientific principles of matter and chemical processes. Designed for grades 6-8, it also includes a simplified version for differentiated learning, an audio component for accessibility, and interactive activities such as multiple-choice questions, writing prompts, and graphic organizers. This comprehensive resource deepens conceptual understanding of atomic structure, chemical reactivity, and the periodic table.

CONTENT PREVIEW

Valence electrons are the outermost electrons of an atom, and they play a central role in chemical reactions. In chemistry, scientists discovered that the way elements combine depends on these electrons. For example, the difference between the explosive reaction of sodium with water and the non-reactive nature of neon can be explained by their valence electrons. Understanding how these electrons work allows scientists to predict chemical properties and create new materials.

How Valence Electrons Determine Chemical Behavior
Atoms are made of protons, neutrons, and electrons. The electrons move in regions called shells around the nucleus. The outermost shell contains the valence electrons. These electrons are responsible for forming chemical bonds with other atoms. Atoms with a full outer shell, such as neon with eight valence electrons, are stable and do not easily react. In contrast, atoms with only one or two valence electrons, like sodium, are highly reactive because they seek to achieve stability by losing or gaining electrons. The periodic table helps us identify the number of valence electrons based on the group number: Group 1 elements have one, Group 6 have six, and Group 8 have eight, making them very stable.

Applications and Real-World Connections
Valence electrons explain why different elements behave differently in the environment and in technology. For example, sodium (Na), with one valence electron, reacts explosively with water. Oxygen (O), with six valence electrons, readily forms bonds to make water and many other compounds. Neon (Ne), with eight valence electrons, is so stable that it does not react with most substances and is used in neon lights because it does not combine with other elements. This knowledge helps chemists design safe materials, medicines, and even new types of batteries.

Interactions, Stability, and the Periodic Table
Valence electrons are also linked to the stability of atoms. Atoms naturally move toward a stable configuration, which usually means having a full outer shell. This drive for stability is what causes atoms to form bonds, creating molecules and compounds. The periodic table groups elements by similar valence electron numbers, so elements in the same group tend to have similar properties and reactivities. This organization has allowed scientists to predict the discovery of new elements and understand complex chemical systems.

In summary, valence electrons are the key to understanding why atoms interact, how molecules are formed, and how the periodic table is organized. They are central to many chemical and technological advances in our world.

Interesting Fact: The noble gases (Group 8), like neon and argon, are so stable because their outer shells are full; this makes them almost completely unreactive, which is why they are used in lighting and to protect sensitive equipment.

What are valence electrons?

The outermost electrons in an atomProtons in the nucleusElectrons found in the innermost shellNeutrons outside the nucleus

According to the passage, what makes neon stable and unreactive?

It has a full outer shell of valence electronsIt has only one electronIt can easily lose electronsIt forms many compounds

Which group on the periodic table has elements with six valence electrons?

Group 6Group 1Group 8Group 2

What is the main function of valence electrons in chemical bonding?

They form chemical bonds with other atomsThey stay in the nucleusThey give atoms their colorThey determine atomic mass

What does the term 'stability' mean in the context of atoms?

Having a full outer shell of electrons and not likely to reactHaving no electrons at allAlways forming new compoundsBeing very reactive

In the passage, what evidence shows that sodium is highly reactive?

It reacts explosively with waterIt glows in neon lightsIt is a noble gasIt forms a full outer shell

Based on the passage, how can scientists predict an element’s chemical properties?

By looking at its group on the periodic tableBy measuring its colorBy counting its neutronsBy checking its atomic mass

Valence electrons are found in the innermost shell of an atom. (True/False)

TrueFalse

Elements in the same group of the periodic table have the same number of valence electrons. (True/False)

TrueFalse

Which of the following best explains why valence electrons are important?

They determine how atoms interact and form compoundsThey are part of the atom’s nucleusThey change the color of elementsThey have no effect on chemical reactions