Atomic Structure — Reading Comprehension

Grades

Standards

MS-PS1-1
RI.6.3
RI.7.1

About This Reader

This reading passage on Atomic Structure provides middle school students with an accessible explanation of the fundamental building blocks of matter. The content aligns with NGSS standard MS-PS1-1 (Develop models to describe the atomic composition of simple molecules and extended structures) and Common Core Reading Standards for Informational Text (Key Ideas and Details). The passage is structured with clear subheadings that guide students through key concepts: what atoms are, the structure of the nucleus, the behavior of electrons, how atoms determine elements, molecule formation, and scientific tools for studying atoms. With a Flesch reading score of 65, this 229-word passage uses simple language and familiar examples like water molecules to make abstract concepts concrete for grades 6-8 students. This resource sits within the Science→Physical Science→Properties of Matter domain and helps students visualize the invisible structures that make up everything in our world.

CONTENT PREVIEW

What Are Atoms?

Have you ever wondered what makes up everything around you? The chair you sit on, the water you drink, and even you yourself are all made of tiny building blocks called atoms. Atoms are so small that millions of them could fit on the head of a pin!

Inside an Atom

An atom is like a tiny solar system. At the center is the nucleus, which contains two types of particles: protons and neutrons. Protons have a positive charge, while neutrons have no charge at all. The nucleus is very dense and makes up most of an atom's mass.

Electrons: The Outer Particles

Around the nucleus, electrons orbit in paths called energy levels or shells. Electrons are much smaller than protons and neutrons, and they have a negative charge. They move so fast that they create a cloud around the nucleus rather than following exact paths.

Elements and Atomic Number

The number of protons in an atom tells us what element it is. For example, hydrogen has one proton, oxygen has eight protons, and gold has 79 protons. In a normal atom, the number of electrons equals the number of protons, making the atom balanced or neutral.

How Atoms Form Molecules

Atoms can gain, lose, or share electrons with other atoms. When they do this, they form bonds and create molecules. Water, for instance, is a molecule made when two hydrogen atoms bond with one oxygen atom.

Studying Atoms

Atoms are the basic units of all matter, yet we cannot see them with our eyes. Scientists use special tools like electron microscopes to study them. The more we learn about atoms, the better we understand our world and how everything in it works together.

Fun fact: If you could enlarge an atom to the size of a football stadium, the nucleus would be only about the size of a pea at the center! This means atoms are mostly empty space.

What two types of particles are found in the nucleus of an atom?

Protons and electronsProtons and neutronsNeutrons and electronsProtons and molecules

How many protons does hydrogen have?

One protonEight protonsSeventy-nine protonsTwo protons

If an atom has 11 protons and 11 electrons, what would happen if it gained 2 more electrons?

It would become a different elementIt would no longer be neutralIt would lose its nucleusIt would become smaller

Based on the passage, why might it be difficult for scientists to study atoms directly?

Atoms move too quicklyAtoms are too small to seeAtoms are too dangerousAtoms change too often

Electrons follow exact, predictable paths around the nucleus.

TrueFalse

In a normal atom, the number of protons equals the number of electrons.

TrueFalse