Chemistry: Mixtures and Compounds

Concept 2.1 Matter consists of chemical elements in pure form and in combinations called compounds

12. Briefly define the following: Matter is anything that takes up space. Element is any substance that can’t be broken down into substances with different properties. Atom is the smallest part of an element that displays the properties of the element.

Background: Paper chromatography is one method for testing the purity of compounds and identifying substances. Paper chromatography is a useful technique because it is relatively quick and requires small quantities of material.

When faced with a problem a good scientist will use experiments, notes, debates, and more to their advantage to solve the tough questions. A groups of scientists did just that when faced with a problem of their own. A tiny vial with a white powdery substance in it was put in front of them, and they needed to find out what was in it! Faced with nine possible ingredients in the “Mystery mixture,” a well tray, a water dropper, and a toothpick, these scientists were a little overwhelmed, but determined. One of the first things they did was look at the substance and compare it to their own mixtures, using experiments or chemical properties. Chemical properties are a chemical’s reaction to another or more substances, and a change in it’s identity. When they observed the chemicals the students were using physical properties, or observing the chemical’s smell, texture, color, appearance, size, and shape. They believe Baking Soda and Citric acid are in the Mystery Mixture.

A mixture, unlike a compound, can be separated by physical means. There are multiple ways in which a mixture can be separated; furthermore, the ways it can be separated is based on what the mixture is made up of.

Since we obtain an unknown proportion of a mixture, it’s important to mention that a mixture is a result of a combination of two or more pure substances that do not react chemically. The physical properties of a mixture depend on its composition because the amounts of each substance making up a mixture can vary. By taking advantage of the unique physical properties of individual components within a mixture, it should be possible to separate a mixture into its components. Mixtures have the following fundamental properties:

1. An Element is a substance that cannot be broken down to other substances by chemical reactions, while a compound is a substance consisting of two or more different elements combined in a fixed ratio.

  Then in 1661, Irish chemist Robert Boyle supported the philosophers’ theory of how chemical elements are made up of the simplest matter, backing the theory of how matter makes up all life and is the smallest living thing (Doc. 1). But a bombshell happened in 1803 when John Dalton backed up all three theories by discovering that atoms make up all matter, and chemical compounds are made of atoms (OI).

Chemical and physical properties of substances are due to the structure and arrangement of atoms, ions or molecules and how these interact with each other

Chemical change results in one or more substances of entirely different composition. Chemical change requires a chemical reaction.

A pure substance is an element or compound with a constant composition, such as salt. Its components stay in a fixed ratio to each other, and they can only be separated by relatively difficult chemical means. A mixture is a physical combination of pure substances. Their compositions vary and it is easy to physically separate them. Mixtures can be either homogeneous or heterogeneous.

If it were a chemical property, bonds would break: the the makeup of the material would change, but that was not the case. The iron in our lab stayed the same. 5. The combination of salt and sand is a mixture. It is a physical combination with no fixed ratio.

Filled with shiny, colorful pictures of elements in their many applications, the book was my first in-depth introduction to chemistry. Two pages were dedicated to each element and explained the most common uses. I started to spend time pondering what was in some of the objects around me. I viewed objects more in their elemental sense rather than “plate material” or “cardboard material”. Since then, I’ve only tried to expand my knowledge of the chemical makeup of my world.

Over the course of the last 5000 years, mankind’s knowledge has been constantly advancing. Chemistry, a branch of science, has experienced a tremendous leap and expansions since ancient Greek civilization. One of the major breakthroughs in the advancement in Chemistry was the creation of the Atomic theory, which laid a foundation for the modern-day Chemistry and future of science. The Atomic theory introduced the idea of atoms, which are defined as the discrete units of matter. There are five key scientists that significantly contributed to the Atomic model over a span of thousands of years. They are: Democritus, John Dalton, J.J. Thompson, Ernest Rutherford, and Niels Bohr.

“What is the world made of?” That question has puzzled scientists and philosophers for centuries. The atomic theory was first proposed in ancient Greece around 400 BC and has continued to evolve through the centuries to finally evolve into the current theory we have today. We now know that the subatomic particles that make up the atom are no longer the fundamental particles of the universe because even they are made of smaller particles called “quarks.” The continuous study of atoms will allow us to truly understand the universe and harness it’s knowledge to further science and technology for the good of society.