The Structure Of An Atom

What Is An Atom?

Atoms are the building blocks of everything around us! We can’t see them with our eyes or even with most microscopes.

The Basic Parts of an Atom:

Nucleus: At the center of every atom is a tiny, dense core called the nucleus. The nucleus is made up of two types of particles:

• Protons: These have a positive charge (+).
• Neutrons: These have no charge; they are neutral.

Electrons: Surrounding the nucleus are even tinier particles called electrons. They move around the nucleus incredibly fast and have a negative charge (-). They are arranged in layers called “shells” or “energy levels.”

 

Changing An Atom’s Structure

Altering the number of protons, neutrons, or electrons in an atom can change its structure.

Adding or Removing Electrons:

• Ionization: When an atom gains or loses electrons, it becomes an ion. Adding electrons gives it a negative charge while removing electrons gives it a positive charge.

Changing the Number of Neutrons:

• Isotopes: Atoms of the same element can have different numbers of neutrons. These variations are called isotopes. For example, carbon-12 and carbon-14 are isotopes of carbon with 6 protons but different numbers of neutrons.

The atomic number of an atom is the number of protons in its nucleus. It is a fundamental property that determines the identity of an element. Each element on the periodic table has a unique atomic number.

Altering the Number of Protons:

• Nuclear Reactions: A nuclear reaction, such as fusion or fission, can change the number of protons, changing the atom into a different element. For example, adding a proton to a hydrogen atom (1 proton) turns it into helium (2 protons).

 

Fun Facts

Here are some interesting facts about atoms:

• Atoms are mostly empty space! If the nucleus were the size of a marble, the nearest electron would be far away, about the size of a football field.
• The Greek word “atomos,” meaning “uncuttable” or “indivisible,” gives us the word “atom” because people believed atoms could not be divided.
• Hydrogen is the most common atom in the universe, making up nearly 74% of the atoms in the Milky Way galaxy.

 

Review

Let’s quickly recap what we learned about the structure of atoms:

• What is the positively charged particle in an atom? Proton
• What is the center of an atom called? Nucleus
• What is the particle with no charge in an atom? Neutron
• What is the negatively charged particle that orbits the nucleus? Electron