Commonly Confused Chemistry Terms


Definitions of chemistry terms may be confusing. (chuttersnap)

Definitions of chemistry terms may be confusing. (chuttersnap)

Learn the difference between two important chemistry terms. Sometimes these words are (incorrectly) used interchangeably. Other times, they are the terms students have a hard time keeping straight. These are differences relating to chemistry and the physical sciences, although you’ll encounter some of these terms in daily life, too.

What Is the Difference Between Chemistry and Chemical Engineering?

Chemistry is the study of matter and its properties. Chemical engineering is applied chemistry, where engineering and science are combined to solve practical problems and make products.

Know the Difference Between a Chemical Property and a Physical Property

A chemical property is a characteristic that can be observed only by performing a chemical reaction, changing the chemistry of a sample.

A physical property is a characteristic that can be observed without changing the chemical identity of a sample. Examples of chemical changes include oxidation states and flammability. Examples of physical properties include color and volume.

What Is the Difference Between Mass and Weight?

Mass is the amount of matter in a sample while weight is how the force of gravity acts upon that mass. On Earth, where gravity acts on all masses, they have equivalent values.

Ionic Versus Covalent Bond

In an ionic bond, one atom essentially loses an electron to another atom. Ionic bonds occur between atoms that have different electronegativities from each other. This occurs between a metal and a nonmetal, as in sodium chloride, NaCl.

In a covalent bond, atoms share electrons. Covalent bonds occur between atoms with comparable electronegativity values, such as two nonmetals. An example of a covalently bonded molecule is water, H2O.

Know the Difference Between Dependent and Independent Variables

In a scientific experiment, the dependent variable is the one being tested while the independent variable is the one that is measured or controlled to test its effect on the dependent variable. For example, if you measure how fast a car moves over time, the speed of the car is the dependent variable and time is the independent variable.

What’s the Difference Between an Atom and an Ion?

An atom is the smallest unit defining an element. Each atom contains at least one proton and usually has neutrons and electrons.

An ion can be an atom or it can be a molecule. In an ion, there are different total numbers of protons and electrons, so an ion carries a net electrical charge. The electrical charge is written as a superscript following the ion symbols. Examples include H+ and OH.

What’s the Difference Between Organic and Inorganic?

Living organisms are made of and synthesize organic molecules. Non-living materials, like rocks and air, consist of inorganic molecules. The easy-to-remember difference is that organic molecules contain carbon, while inorganic molecules usually do not. There are some exceptions, such as carbon dioxide, which contains carbon yet is considered an inorganic compound. Organic molecules always contain hydrogen in addition to carbon.

Know the Difference Between Accuracy and Precision

Accuracy and precision both describe how good a set of measurements are, but accuracy is how close measurements are to a true value, while precision reflects how close measurements are to each other or how reproducible something is.

Know the Difference Between Element Groups and Periods

Groups and periods are sets of elements that share common properties. On a periodic table, element groups are vertical columns, while element periods are horizontal rows.

What Is the Difference Between a Cation and an Anion?

A cation is an ion that carries a positive charge. Examples include Na+, H3O+, and Mg2+. An anion is an ion that carries a negative charge. Examples include OH and SO42-.

What Is the Difference Between Control Group and Experimental Group?

Control groups are used in some experiments to help isolate the effect of the independent variable on the results. The experimental group is exposed to the independent variable, while the control group is kept under identical conditions, except not exposed to this variable,

For example, if you are testing whether supplementing a diet with zinc prevents colds, the experimental group would be given supplemental zinc while the control group would not.

What Is the Difference Between Steam and Smoke?

Steam and smoke often look similar to each other, but they are different types of vapor. Steam is water vapor, the gaseous form of water. Smoke is formed by combustion and consists of several gases, including steam, carbon oxides, and sulfur oxides, and also particulates such as soot.

Is There a Difference Between Flammable and Inflammable?

If something is flammable, it can catch fire readily. Although you might think inflammable would mean the opposite, it turns out inflammable also refers to anything that catches fire easily. The two words mean exactly the same thing! The opposite of flammable or inflammable is nonflammable.

What Is the Difference Between Sodium and Salt?

Sodium is a chemical element. Salt commonly refers to sodium chloride, a compound which contains sodium and also chlorine. However, in chemistry, a salt technically is any ionic compound formed from reacting an acid with a base, For example, magnesium chloride is a salt which does not contain any sodium.

What Is the Difference Between Oxidation and Reduction?

Oxidation and reduction are two types of chemical reactions, commonly found together. During oxidation, a reactant loses electrons. During reduction, a reactant gains electrons.

What Is the Difference Between Heterogeneous and Homogeneous?

Heterogeneous refers to mixtures that are not uniformly distributed. You can identify them based on their appearance. There will be areas containing more of one color or texture than other areas. Examples of heterogeneous mixtures include a handful of candies, a pile of rocks, or Rocky Road ice cream.

Homogeneous mixtures have the same composition in every part of the mixture. Examples of homogeneous mixtures include air, blood, and salt water.

What Is the Difference Between Molarity and Normality?

Both molarity and normality are ways of expressing the concentration of a chemical solution. Molarity is the number of moles of solute per liter of solution. It is denoted with a capital letter M, as in a 1.0 M solution of HCl.

Normality is the gram equivalent weight per liter of solution. In some cases, molarity and normality are the same, but when a chemical species is only partly soluble or else fully dissociates in a solution, molarity and normality may be quite different. Normality is denoted with a capital letter N, as in a 1.0 N solution of H2SO4.

What Is the Difference Between a Molecule and a Compound?

For the most part, you’ll hear people use the terms “molecule” and “compound” interchangeably. Some texts define a molecule as any chemical species formed when two or more atoms bond together and a compound as a molecule made up of two or more different types of atoms. Oxygen gas, O2, is a typical molecule example. Table salt, NaCl, is a good example of a compound.

What Is the Difference Between Metals and Nonmetals?

The chemical elements can be divided into two groups: metals and nonmetals. Some elements have intermediate properties and are called semimetals or metalloids.

Most elements are metals. Metals readily lose electrons. They tend to be hard, shiny, dense conductors. Nonmetals readily gain or share electrons. They tend to be softer than metals, not as lustrous, and brittle. While most metals are solids at room temperature, nonmetals are found as solids, liquids, and gases.

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