Hi Jacob, great question! I'm glad you're asking such tough questions at such a young age!

Let's start basic, and then we'll answer your question. Everything is made of something, right? For example, a building is made of bricks, bricks are made of clay, clay is made of elements, and each element is made up of atoms. We can see the brick with our eye, but if we could keep on zooming in further and further with a microscope, we could eventually see the smallest things that make up a brick--those things are called atoms. Think of atoms like the smallest building bricks of life! Everything is made of atoms--stars, rocks, and even you and I!

There are many different types of atoms: carbon, oxygen, nitrogen, and many many more! To stay organized, we often learn about atoms in the form of something called a "periodic table." You'll learn about that later, but now we have enough information to answer your question:"what is the similarity between oxygen and carbon dioxide?" I'm guessing you're asking about oxygen gas and carbon dioxide gas, so let's discuss.

Remember that oxygen is an atom. If oxygen was a person, it would be a really "friendly" atom because it gets lonely by itself, so it prefers to play with other atoms. The oxygen that is found in the air we breathe is actually two oxygen atoms that are attached to each other, because they like hanging out together. That's why we call oxygen gas "O₂."

The carbon dioxide gas that is also found in the air that we breathe is basically just two oxygen atoms who decided to let a carbon atom join the party, so now there are three atoms hanging out together and we call this gas "CO₂" because there's one carbon and two oxygens hanging out together!

So to answer your question: the main similarity between carbon dioxide gas and oxygen gas is that both of them are gases with individual molecules that have two oxygens. I hope that helps! Keep asking good questions.

Well diatomic oxygen (two atoms of oxygen together) is a linear molecule O=O where the bond is a double bond.

CO₂ is a linear molecule as well O=C=O

But these gases have different properties … O₂ becomes a liquid at about 93 K (Kelvin degrees) at room pressure (1 bar) whereas CO₂... look at the diagram for CO₂ at the end.

The phase diagram for oxygen looks like this : at atmospheric pressure O₂ solid melts at about -220 Centigrade (C) or about 53 K (Kelvin) and then it boils (becomes gas at about -175 deg C or about 93 K).

CO₂ has a phase diagram like: this.

Do you notice the difference in both diagrams? If you cannot read these diagrams, please ask your teacher or a grown up to help you.

Both oxygen and carbon dioxide are gases unless we drop the temperature really, really, really low. Furthermore, oxygen is a part of both oxygen (O₂ and carbon dioxide CO₂.

Assuming the molecular oxygen (O₂) that is the most common form, both O₂ and CO₂ are molecules, have 2 oxygen atoms, and are gases around room temperature and pressure. Both are non-polar overall, but CO₂ has slightly polar bonds (carbon slightly positive and the oxygens slightly negative).

Both O₂ and CO₂ are linear molecules. However, O₂ reacts readily with many other elements and compounds (e.g., rust is iron oxide; water is hydrogen and oxygen; sand is mostly silicon and oxygen). CO₂ is generally less reactive and this non-reactivity is why it is used in welding and fire suppression. Another common use of CO₂ is to carbonate drinks, because it leads to carbonic acid that produces an enjoyable mouthfeel. The two also behave differently as temperature is reduced at atmospheric pressure, with O₂ turning to liquid at -183 C and freezing at -215 C, while CO₂ cannot be liquid unless additional pressure is applied and it solidifies at a relatively high -79.5 C.

(1)They are both gasses.
(2) Both contain two atoms of oxygen per molecule.

Carbon dioxide also has a carbon atom, which oxygen does not.

Oxygen and carbon dioxide are both gases, this is what makes them similar. However, Oxygen (formula O₂) is an element,  a substance that cannot be separated into simpler substances by chemical means. We find oxygen in nature, always in pairs of atoms, that is why we write O₂, which means two atoms of oxygen.

Carbon dioxide is not an element, but it is a compound, which means that it is made of different atoms, in this case one atom of Carbon (C), and two atoms of oxygen (O₂).  The chemical formula for carbon dioxide is CO₂.

Oxygen and carbon dioxide are both molecules, meaning they are made of multiple atoms bonded together.

An oxygen molecule is two oxygen atoms bonded together, and carbon dioxide is a carbon atom bonded to two different oxygen atoms. So they both contain two oxygen atoms. They also both make up a portion of our atmosphere, even though there is a lot more oxygen in the atmosphere than carbon dioxide.

Oxygen is involved in respiration, which is a process that happens when we breathe and produce carbon dioxide. Carbon dioxide is used in photosynthesis, a process during which plants produce oxygen!