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Chemical Bonds — Reading Comprehension

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MS-PS1-1
RI.6.3
RI.7.1

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This reading passage on Chemical Bonds provides middle school students with a clear explanation of how and why atoms connect to form molecules and compounds. Aligned with NGSS standard MS-PS1-1 (Develop models to describe atomic composition of simple molecules) and PS1.A (Structure and Properties of Matter), the content uses a structured approach with informative headings to organize key concepts. The passage first introduces chemical bonds as forces holding atoms together, then explores three main bond types: ionic bonds (complete electron transfer between unlike atoms), covalent bonds (electron sharing between similar atoms), and hydrogen bonds (weaker connections involving hydrogen). Real-world examples like table salt and water make abstract concepts concrete. This resource falls within Science→Physical Science→Chemical Reactions and uses straightforward language to help students understand how different bonding patterns determine the physical and chemical properties of substances they encounter daily.

CONTENT PREVIEW

"Rough diamond" / U.S. Geological Survey / Wikimedia Commons.

What is a Chemical Bond?

A chemical bond is the force that holds atoms together in molecules and compounds. Think of it as the "glue" that connects atoms to each other. When atoms join together through chemical bonds, they create more stable arrangements than they would have on their own.

Types of Chemical Bonds

Ionic Bonds

Ionic bonds form when one atom completely transfers electrons to another atom. This happens between atoms that have very different properties - usually a metal and a non-metal. When an atom loses electrons, it becomes a positively charged ion. When an atom gains electrons, it becomes a negatively charged ion. These opposite charges attract each other strongly, creating an ionic bond. Table salt (sodium chloride) is a classic example, where sodium atoms donate electrons to chlorine atoms.

Covalent Bonds

Covalent bonds form when atoms share electrons rather than transferring them. This typically happens between non-metal atoms. By sharing electrons, both atoms can fill their outer electron shells and become more stable. Water (H₂O) is a perfect example, where oxygen shares electrons with two hydrogen atoms.

Hydrogen Bonds

Hydrogen bonds are weaker connections that form when a hydrogen atom bonded to a highly electronegative atom (like oxygen or nitrogen) is attracted to another electronegative atom. Though individually weak, many hydrogen bonds together can be quite strong. These bonds give water its unique properties and help shape proteins and DNA.

Why Chemical Bonds are Important

Chemical bonds determine the properties of substances - whether something is a gas, liquid, or solid; whether it conducts electricity; how it reacts with other substances; and even its color and odor. Everything from the air we breathe to the materials in our homes exists because of these different types of atomic connections.

Fun fact: The reason diamonds are so hard while graphite (pencil lead. is so soft comes down to chemical bonds. Both are made entirely of carbon atoms, but in diamonds, each atom forms strong bonds in a rigid 3D structure, while in graphite, the atoms form strong bonds in flat sheets with weak connections between layers, allowing them to slide apart easily when you write!

What is a chemical bond?

A type of moleculeThe force that holds atoms togetherA charged particleThe center of an atom

Which type of bond involves the complete transfer of electrons?

Covalent bondHydrogen bondIonic bondMetallic bond

In a covalent bond, atoms:

Transfer electronsShare electronsRepel each otherChange into different elements

Which substance is an example of ionic bonding?

Water (H₂O)Table salt (NaCl)Carbon dioxideDNA

Hydrogen bonds are typically:

The strongest type of chemical bondOnly found in waterWeaker than ionic and covalent bondsFound only between metals

Chemical bonds determine all of the following EXCEPT:

Whether a substance is solid, liquid, or gasThe number of protons in an atomHow a substance reacts with other substancesWhether a substance conducts electricity

The word "electronegative" in the passage most likely refers to:

Atoms that easily lose electronsAtoms that strongly attract electronsAtoms with no electrical chargeElectrons with negative charges

According to the passage, why do atoms form chemical bonds?

To become more stableTo create new elementsTo increase their atomic numberTo release energy