The topic of Atoms and Molecules is directly and indirectly included in the GED test.
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Video Transcription
Chemistry is the study of matter which is everything around us. All matter is made up of tiny pieces called molecules but even molecules are made of smaller parts called atoms. Atoms have a center called a nucleus which contains protons and neutrons. There are also electrons that move around the nucleus.
Some atoms slowly break down over time. When the nuclei of these atoms decay, they release energy particles. These particles are called radioactive because they come from the nucleus, and this process is called nuclear radiation. Some radioactive elements, like uranium, can be very dangerous, while others are harmless.
Matter can be divided into elements, compounds, or mixtures:
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Let’s start with elements. These are pure substances that can’t be broken down into anything simpler. They’re made of just one type of atom. For example, oxygen is an element and its chemical symbol is O. Hydrogen is another element with the symbol H. And then there’s carbon, which has the symbol C.
Then, we have compounds. These are substances made from two or more elements that are chemically combined in a specific way. Compounds have different properties from the elements they are made of. For example, water is a compound made of hydrogen and oxygen. The chemical formula for water is H2O, meaning it has two hydrogen atoms and one oxygen atom.
Many compounds can be classified as either an acid or a base. Acids, such as lemon juice, taste sour. Bases neutralize acids; an example of a base is baking soda.
And finally, we have mixtures, these are combinations of two or more substances that are not chemically combined. Each substance in a mixture keeps its own properties. An example of a mixture is salt water.
Here is a sample question:
Water (H2O) is a molecule that contains two hydrogen atoms (H) and one oxygen atom (O).
If you have 2 molecules of water, how many hydrogen atoms do you have in total?
Option A. 2
Option B. 4
Option C. 6
Option D. 8?
The correct answer is option B,
Each molecule of water (H2O) contains 2 hydrogen atoms. Therefore, 2 molecules of water will have: 2 times 2 hydrogen atoms which is 4.
Let’s solve a few quizzes to ensure you understand these concepts.
Last Updated on October 20, 2025.