(1) Elements and atoms | Atoms, compounds, and ions | Chemistry | Khan Academy

Study Guide: Unit One - Introduction to Atoms in AP Chemistry

What is an Atom?

  • An atom is like a tiny building block that makes up everything around us. Think of it like a LEGO piece that can join with other pieces to create all sorts of things!

Parts of an Atom:

  1. Protons

    • These are positive little particles found in the center (nucleus) of the atom.

    • They help determine what kind of atom it is. For example, if there are 1 proton, it's hydrogen!

  2. Neutrons

    • These are neutral particles (they have no charge) also found in the nucleus.

    • They help keep the atoms stable. If you change the number of neutrons, you get a different version of the atom called an isotope.

  3. Electrons

    • These are tiny particles with a negative charge that whiz around the nucleus in paths called orbitals.

    • They are much smaller than protons and neutrons and can be added or removed to make different types of atoms, like ions.

Simple Model of an Atom:

  • Imagine a tiny ball (the nucleus) in the center with some small dots racing around it. The ball has more weight than the dots because protons and neutrons are heavier than electrons!

Practice Problems:

  1. Identify the Atom

    • How many protons, neutrons, and electrons are in a neutral carbon atom?(Hint: Carbon has 6 protons.)

  2. Isotopes

    • If you have an atom with 6 protons and 8 neutrons, what is this isotope of carbon called?(Hint: It has a special name based on the total number of protons and neutrons.)

  3. Electron Changes

    • What happens to an atom of sodium (which has 11 electrons) when it loses one electron? What charge does it have now? (Hint: Losing an electron makes it positive!)