Use the following formula to find the percent error:

For this experiment, our accepted value is the same as the theoretical value.

Percent error is a calculation usually completed at the end of an experiment for data analysis. It is in essence a tool that can be used to calculate the precision of your calculations. This can be done by following the equation:

Experimental represents that value that was experimentally obtained. Accepted represents that value that would have been accepted. 

This quickly turns into a "plug and chug" type of problem. 

For this problem:

experimental: 

accepted: 

To find the percent error we need to use the following equation:

But in order to do this, we first have to convert moles of sodium oxide into grams:

This gives us a theoretical yield of 248g, which we plug in with our 195g actual yield.

To find the percent error we need to use the following equation:

But in order to do this, we first have to convert moles of sodium oxide into grams:

This gives us a theoretical yield of 248g, which we plug in with our 195g actual yield.

The identity of an element is determined by the number of protons. One cannot alter the number of protons without altering the identity of the element. By adding a proton, the atomic number increases by one and the element identity changes.

Number of neutrons can be altered to create isotopes. Number of electrons can be altered to create ions.

An element is defined by its number of protons. Varying the number of neutrons will change the isotope of an element and varying the number of electrons will create an ion, but changing the number of protons changes the identity of the element itself. Nitrogen has atomic number seven, and is the only element that can have seven protons. The given configuration is for an isotope of nitrogen. Since there are eight neutrons, this atom would be for nitrogen-15.

Elements are shown on the periodic table. Compounds are made when one or more element is combined to form a molecule. The smallest unit of an element is an atom, while the smallest unit of a compound is a molecule.

Of the given answer choices, only satisfies the question criteria. This is the formula for a molecule of bromine gas, made of two bromine atoms.

is a sodium ion, representing one atom of sodium that has lost an electron to gain a positive charge. Though it contains only one element, it is not a molecule. is a single carbon atom, and also does not represent a molecule.

is the formula for hydrochloric acid and is the formula for water. Both of these compounds are composed of molecules, but hydrochloric acids contains both hydrogen and chlorine atoms, and water contains both hydrogen and oxygen.

Elements are defined by the number of protons in a given atom, and the atom is the smallest unit of an element. In contrast, a compound is defined by the identity and organization of multiple atoms, with the smallest unit of a compound being a molecule.

Some compounds do contain only one element, such as diatomic gases or graphite. Benzene rings are composed of carbon and hydrogen, while water molecules contain hydrogen and oxygen.

There are two properties that can be used to identify an element: the atomic number or the number of protons in an atom.

The number of neutrons and number of electrons are frequently equal to the number of protons, but can vary depending on the atom in question. Different ions and isotopes will alter the number of neutrons and electrons, making these properties unreliable identifiers. Similarly, atomic mass will vary with the number of neutrons present and cannot be used to establish atomic identity.

Diatomic elements are commonly referred to as diatomic gases because whenever they are by themselves, they bond to themselves (that is where the "2" subscript comes from). Anytime diatomic elements have that "2" subscript, they have the gas (g) phase label. For example, .