Chemical Reactions

Chemical reactions are the making or breaking of bonds between atoms. The number of atoms remain the same. Through chemical reactions, substances are changed on an atomic level creating new molecules with distinct characteristics which are different than their component atoms or molecules.

A physical reaction does not change the molecules or atoms involved, but rather changes their state or phase, as in converting from a liquid to a gas.

When different things mix together, sometimes they can create new things! This is called a chemical reaction. It's like when you mix colors of paint to make a new color.

In a chemical reaction, the tiny pieces that make up everything (atoms) can stick together or break apart to create new things. But the number of atoms stays the same - it's just that they've rearranged themselves into something different.

The new thing that's created can have different properties than the original things. It might be a solid instead of a liquid, or it might have a different color or smell.

A physical reaction is different because it doesn't create something new. It just changes the way something looks or feels. Like when you put ice in your hand and it melts into water - it's still the same stuff, just in a different form.

Hey there! Sometimes when we mix different things together, they can create new things! This is called a chemical reaction. It's like when you mix different colors of paint to make a new color.

During a chemical reaction, the tiny pieces that make up everything (atoms) can stick together or break apart to create new things. But the number of atoms stays the same - it's just that they've rearranged themselves into something different.

The new thing that's created can have different properties than the original things. It might look or feel different, or even have a different smell.

A physical reaction is different because it doesn't create something new. It just changes the way something looks or feels. Like when ice melts into water, it's still the same thing - just in a different form.

Collision Theory

Collision Theory

Collision theory is one potential explanation for the occurrence of chemical reactions. It states that atoms, ions or molecules are continuously colliding, thus providing opportunities for chemical reactions to occur.

Bond formed releasing energy

Bond breaks releasing energy

All atoms, ions, and molecules are continuously moving and are thus continuously colliding with one another. These collisions can disrupt electron structures powerfully enough to break chemical bonds, thus forming new bonds and new molecules.

Have you ever played pool or billiards? When you hit one ball with the cue ball, it can bounce off and hit another ball. This is kind of like what happens in collision theory!

Collision theory is a way to explain how chemical reactions happen. It says that in order for two things to react with each other, they have to bump into each other first.

Think of it like people in a crowded room. If you want to talk to someone, you have to walk over to them and start a conversation. If you never bump into them, you'll never get to talk to them!

It's the same with chemical reactions. The two things that want to react with each other have to bump into each other first. But not just any bump will do - they have to hit each other hard enough and in the right way to make the reaction happen.

So, like when you hit a pool ball with the cue ball, the two balls have to hit each other hard enough and in the right way to bounce off each other. In the same way, two things have to hit each other hard enough and in the right way to make a chemical reaction happen.

Energy in Chemical Reactions:

Chemical reactions can produce or absorb energy.

Chemical energy is the net gain or loss of energy that occurs during a chemical reaction. All chemical bonds require energy when they are broken and release chemical energy when they are formed. The release of energy is an endergonic reaction; the absorption of energy is known as an exergonic reaction.

While chemical reactions are generalized, there are many different ways in which bonds can be broken or created. These include (but are not limited to) synthesis, decomposition, exchange, reverse, and oxidation-redox.

Did you know that chemical reactions can make energy, or use up energy? It's kind of like how you need energy to run around and play, but then you also get tired and need to rest to get more energy.

When different things mix together in a chemical reaction, they can make or use up energy. This is called chemical energy.

When the things mix together and create new bonds, they release energy - kind of like a burst of energy that can be used for other things. This is called an exergonic reaction.

But sometimes, when the things mix together and the bonds break, they need energy to do it. This is called an endergonic reaction - it's like they're taking in energy instead of releasing it.

There are lots of different ways that the things can mix together and make or use up energy. Some ways are called synthesis, decomposition, exchange, reverse, and oxidation-redox. These are just fancy names for different types of chemical reactions.

So just like how your body uses energy to run around and play, chemical reactions can also make or use up energy in different ways.

Exergonic and Endergonic Reactions

The exchange of energy during a chemical reaction is either exergonic (releasing of energy) or endergonic (absorbing of energy).

While the terms exergonic and endergonic are used to describe energy states in chemical reactions, these vocabulary words aren't limited to just chemical reactions.

Exergonic reaction:

Endergonic reaction:

When different things mix together in a chemical reaction, they can release energy, or they might need to use up energy.

When the things mix together and release energy, it's called an exergonic reaction. Kind of like how a rocket blasting off releases a lot of energy - it goes zooming into the sky!

But sometimes, the things mixing together need to use up energy to do it. This is called an endergonic reaction. It's kind of like when you're trying to climb a really steep hill - you need to use up a lot of energy to make it to the top.

These are big words, but they're not just used for chemical reactions - they can be used to describe other things too! For example, when you jump off a diving board, you're doing an exergonic reaction - you're releasing a lot of energy when you jump! But when you climb up the ladder to get to the diving board, that's an endergonic reaction - you're using up energy to get to the top.

So, exergonic and endergonic reactions are just ways to describe how things release or use up energy - in chemical reactions and in other things too!

Synthesis Reaction

When two or more atoms, ions, molecules combine to form new and larger molecules. To synthesize means to put together. A synthesis reaction forms new bonds.

Synthesis Reaction:

The combining substances, A and B, are called the reactants; the substances formed by the combination, AB, is the product.

Example of a synthesis reaction:

Pathways of synthesis reaction in living organisms are collectively called anabolic reactions, or simply anabolism. The combining of sugar molecules to form starch and of amino acids to form proteins are two examples of anabolism.

Synthesis reactions are a type of chemical reaction where two or more things mix together and make something new.

It's kind of like when you're baking a cake. You mix together flour, sugar, eggs, and butter, and when you bake it in the oven, it turns into a yummy cake!

In a synthesis reaction, the things that mix together are called reactants, and the new thing that's made is called the product.

So, for example, if you mix hydrogen and oxygen together, they can do a synthesis reaction and make water! It's pretty cool how different things can come together to make something totally new.

Decomposition Reaction

A decomposition reaction is the opposite of a synthesis reaction. Bonds are broken in a decomposition reaction, resulting in smaller molecules, ions, or atoms. Catabolic reactions are decomposition reactions which occur in living cells. A decomposition reaction occurs in the following way:

Hey there! Decomposition reactions are the opposite of synthesis reactions. Instead of things mixing together to make something new, they break apart into smaller pieces.

It's kind of like when you take apart a Lego tower - you're breaking it down into smaller pieces.

In a decomposition reaction, one thing (which is the reactant) breaks down into two or more smaller things (which are the products).

For example, if you heat up baking soda, it will do a decomposition reaction and break down into carbon dioxide gas, water, and a type of salt called sodium carbonate.

So, decomposition reactions are all about breaking things down into smaller pieces instead of putting things together to make something new.

Example of a decomposition reaction:

Exchange Reaction

Exchange reactions are a type of chemical reaction where two different things swap or exchange parts with each other.

All chemical reactions consists of synthesis and decomposition reactions, exchange reactions are a combination of the two happening sequentially.

First, the bonds between AB and between CD are broken in a decomposition process. New bonds are then formed between A and D and between C and B in a synthesis process.

Exchange reaction work in the following way:

Exchange reactions are a type of chemical reaction where two different things swap or exchange parts with each other.
It's kind of like if you and your friend had different colored candies, and you decided to trade some of your candies with your friend's. You both end up with some of each other's candies, but you still have some of your own too.
In an exchange reaction, the reactants switch some of their parts with each other to make new products. So, instead of breaking apart or combining like in synthesis or decomposition reactions, they're just trading some of their parts.
For example, if you mix hydrochloric acid and sodium hydroxide together, they can do an exchange reaction where the hydrogen from the acid switches places with the sodium from the hydroxide. The end result is table salt and water!
So, exchange reactions are all about swapping parts between different things to make something new.

Reverse Reaction

Reverse reactions occur when the end product of a chemical reaction can revert to the original molecule type it was before the reaction.

Reversible reactions occur mainly due to neither the reactants nor the end product are very stable. Some reactions reverse only under special conditions.

A reversible reaction is indicated by two arrows, as shown here:

Sometimes, after a chemical reaction happens, the products that were made can react together to make the original reactants again. That's called a reverse reaction!

It's kind of like if you build a Lego tower, but then you decide you want to take it apart and build something else instead. You can reverse the process of building the tower by taking it apart, and then use the same pieces to build something new.

In a reverse reaction, the products from the original reaction become the reactants, and the reactants from the original reaction become the products. This can happen if conditions change, like temperature or pressure.

For example, if you mix baking soda and vinegar together, they react to make carbon dioxide gas, water, and a type of salt called sodium acetate. But if you heat up the sodium acetate and water mixture, you can cause a reverse reaction to happen where the carbon dioxide gas goes back into the solution and the original baking soda and vinegar are made again.

So, reverse reactions are all about undoing a chemical reaction by making the products become the reactants again.

Oxidation-Reduction (redox) Reaction

An oxidation and reduction (shortened to redox) reaction is the phenomenon in which electrons are transferred from one atom or molecule to another to create a new molecule.

These reactions are actually two reactions happening at the same time: oxidation and reduction. In an oxidation reaction, electrons are taken away from a substance, while in a reduction reaction, electrons are given to a substance. When these two reactions happen together, they create a lot of energy.

These reactions are always happening together, which means that every time a substance is oxidized (loses electrons), another substance is reduced (gains electrons).

Oxidation and redox reactions are a type of chemical reaction that happen when electrons are transferred between different atoms or molecules.

In an oxidation reaction, electrons are taken away from a substance. This means that the substance loses electrons and becomes more positive. In a redox reaction, both oxidation and reduction reactions happen at the same time. So, while one substance is losing electrons, another substance is gaining them.

These reactions are important because they can create energy, like in batteries, or they can break down substances into different components. Oxidation and redox reactions happen all around us, and they're a big part of how things work in the world of science!

Example of an oxidation reaction:

Compound A loses an electron to compound B. Compound A has undergone oxidation, whereas Compound B has undergone reduction.

When Na and Cl react to form sodium chloride (NaCl), a sodium atoms gives up electron to chlorine atoms. During this reaction, sodium is oxidized because it loses an electron, and chlorine is reduced because it gained an electron.

The metabolic work of cells revolves around energy exchanges and transfers. Most cells are too delicate to operate under the conditions of physical reactions. Yet chemical reactions allow the transfer of energy. Electrons in the outermost shell easily give up electrons because they are farther away from the nucleus of an atom. This is why electrons can transfer/pulled away to other atoms easily. A cell must have a supply of atoms that can gain or lose electrons to carry out life processes.

Every cell in our body needs energy to do its job. This energy comes from chemical reactions that happen inside the cell. These reactions allow energy to be transferred between molecules.

Cells are very delicate, and they can't handle the conditions of physical reactions like fire or explosions. But chemical reactions happen in a way that's safe for the cell. In these reactions, electrons can be transferred between atoms to make new molecules.

Atoms are made up of a nucleus in the center, with electrons buzzing around on the outside in something called shells. Electrons that are in the outermost shell are easy to take away or share with other atoms. This is why they can be transferred to other atoms so easily.

For a cell to function properly, it needs a supply of atoms that can gain or lose electrons. This allows the cell to create new molecules and transfer energy between them. This process is called metabolism, and it's what allows cells to carry out all the processes they need to keep us alive!