5 Paragraph Essay Chemical Reactions

Physical and Chemical Reactions


Chemical reactions are when a reactant or starting substance is chemically combined with another reactant to make a product. When the reactants combine they change the properties and other characteristics in chemical reaction happens, because of molecules, atoms or compounds. Physical reaction is when an object changes it appearance or shape. Physical reaction is also known as physical change.

Five Types Of Chemical Reactions

There are five types of chemical reactions.

  1. Synthesis this is when two reactants combine and make a compound.
  2. Decomposition is when a compound is broken down into two elements.
  3. Single replacement this is when one element replaces second elements.
  4. Combustion when a element or a compound reacts to an oxygen and produces heat or light.
  5. Double replacement when positive ions exchange two compounds.

Chemical Change

Chemical change is another name for chemical reaction. Some formulas are carbon plus 02 or 2 oxygen particles equals to carbon dioxide or CO2. There s HC2H3O2 or vinegar, this equals to three products, first is carbon dioxide, second is H2O, last is sodium acetate. sodium acetate is a crystalline salt that attracts moisture from the air. Is a starting substance, and a new substance. The starting substance is called a reactant, and the new substance is called a product. For example: Carbon + oxygen = Carbon dioxide. Carbon and oxygen are the reactants, and the product is carbon dioxide. Another way of saying carbon plus oxygen is, c+o2=co2. The aroms are the ones that turn an object rusty, reddish, and many more.NaHCO3 or baking soda plus HC2H3O2 or vinegar, this equals to three products, first is carbon dioxide, second is H2O, last is sodium acetate. sodium acetate is a crystalline salt that attracts moisture from the air.

Physical Change

Physical change is the opposite of chemical change. They are different from each other because physical change is not changed by atoms. Not like chemical change the size and shape of an object is changed, not by chemicals, but by other objects. Here are some example of physical change: tearing a piece of paper,breaking glass,and hammering nails into wood and many more. Here are some examples of physical properties: texture, shape, size, odor, and many more. There are no formulas for physical change, because it is not changed by atoms. Physical change is happenning everywhere.

Reactive Elements

These are the most reactive metal elements and most reactive nonmetal elements, Alkali metal and Halogens. In the Alkali Metals there is Lithium, Sodium, Potassium, Cesium, Rubidium and Francium. Francium has the highest reactivity, because of the atomic number of 87, an atomic number is the number of protons, electrons and neutrons in an atom.In alkali metals family the one that has the highest atomic number is the most reactive. In the Halogens there is Fluorine, Chlorine, Bromine, Iodine and Astatine. In the Halogens the one with the least atomic number is the most reactive, that is Fluorine, because it has the atomic number of nine. In the periodic table the halogens are in the right, and the alkali metals are in the left. So you can read the periodic table here are the abreviations for halogens and alkali metals. Halogens: Fluorine (F), Chlorine (Ch), Bromine (Br), Iodine (I), and Astatine (At). Alkali Metals: Lithium (L), Sodium (Na), Potassium (K), Rubidium (Rb), Cesium (C), and Francium (Fr).




light orange-alkali metals yellow-Halogens

Signs of chemical change

There are many signs of chemical change, but we will only tell you guys some.

  1. Precipitate is when a solid is formed because of a chemical reaction
  2. Temperature change is when the temperature goes up or down chemically
  3. Color change is when an object’s color changes due to an atom.
  4. When something produces gas, it is a sign of chemical change. It is when antacid makes gas when it is in the water.


The most important chemical reaction helps living things like us live and breathe. That chemical reaction is called photosynthesis. This first starts when the sun rays, the light from the sun that makes it to earth goes through this process. When this energy hits the plants the reaction starts and the plant absorbs specific parts of the light. The part of, this chloroplast this is a plastid or a thin covering of cells is a green colored matter of plants, this has chlorophyll molecules and the molecules go into an area called the Stroma. This is a matrix of cells. Chlorophyll it is a green colored matter of plants. This reaction is divided into two groups, the light dependent reaction and light independent reaction. The formula to this is carbon dioxide plus water equals to glucose and oxygen.


Respiration is the reverse of photosynthesis. The body cells in your body forcesglucose and oxygen to mix their atoms up turning into carbon dioxide, also known as co2, and water (h2o). It releases stored energy you can use to run, work, play, learn, and most importantly, live. Respiration is also an important chemical reaction. In fact, it is just as important as photosynthesis. People and animals cannot live without respiration. The formula to respiration is, glucose plus oxygen equals to the first product of carbon dioxide and water.


Sometimes chemical reactions could be dangerous, and sometimes it helps us with our lives. Reactivity is important, because without it we wouldn’t have the things we have today and our lives!

Like this:


Chemical reaction, a process in which one or more substances, the reactants, are converted to one or more different substances, the products. Substances are either chemical elements or compounds. A chemical reaction rearranges the constituentatoms of the reactants to create different substances as products.

Chemical reactions are an integral part of technology, of culture, and indeed of life itself. Burning fuels, smeltingiron, making glass and pottery, brewing beer, and making wine and cheese are among many examples of activities incorporating chemical reactions that have been known and used for thousands of years. Chemical reactions abound in the geology of Earth, in the atmosphere and oceans, and in a vast array of complicated processes that occur in all living systems.

Chemical reactions must be distinguished from physical changes. Physical changes include changes of state, such as ice melting to water and water evaporating to vapour. If a physical change occurs, the physical properties of a substance will change, but its chemical identity will remain the same. No matter what its physical state, water (H2O) is the same compound, with each molecule composed of two atoms of hydrogen and one atom of oxygen. However, if water, as ice, liquid, or vapour, encounters sodium metal (Na), the atoms will be redistributed to give the new substances molecular hydrogen (H2) and sodium hydroxide (NaOH). By this, we know that a chemical change or reaction has occurred.

Historical overview

The concept of a chemical reaction dates back about 250 years. It had its origins in early experiments that classified substances as elements and compounds and in theories that explained these processes. Development of the concept of a chemical reaction had a primary role in defining the science of chemistry as it is known today.

The first substantive studies in this area were on gases. The identification of oxygen in the 18th century by Swedish chemist Carl Wilhelm Scheele and English clergyman Joseph Priestley had particular significance. The influence of French chemist Antoine-Laurent Lavoisier was especially notable, in that his insights confirmed the importance of quantitative measurements of chemical processes. In his book Traité élémentaire de chimie (1789; Elementary Treatise on Chemistry), Lavoisier identified 33 “elements”—substances not broken down into simpler entities. Among his many discoveries, Lavoisier accurately measured the weight gained when elements were oxidized, and he ascribed the result to the combining of the element with oxygen. The concept of chemical reactions involving the combination of elements clearly emerged from his writing, and his approach led others to pursue experimental chemistry as a quantitative science.

The other occurrence of historical significance concerning chemical reactions was the development of atomic theory. For this, much credit goes to English chemist John Dalton, who postulated his atomic theory early in the 19th century. Dalton maintained that matter is composed of small, indivisible particles, that the particles, or atoms, of each element were unique, and that chemical reactions were involved in rearranging atoms to form new substances. This view of chemical reactions accurately defines the current subject. Dalton’s theory provided a basis for understanding the results of earlier experimentalists, including the law of conservation of matter (matter is neither created nor destroyed) and the law of constant composition (all samples of a substance have identical elemental compositions).

Thus, experiment and theory, the two cornerstones of chemical science in the modern world, together defined the concept of chemical reactions. Today experimental chemistry provides innumerable examples, and theoretical chemistry allows an understanding of their meaning.

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