An element is a pure substance made up of only one type of atom, while a compound is a substance made up of two or more elements chemically bonded together.
A physical change is a change in the physical properties of a substance, such as shape or state, without changing its chemical composition. A chemical change, on the other hand, involves a rearrangement of atoms and results in the formation of a new substance with different properties.
To calculate the number of moles in a sample, you divide the mass of the sample by the molar mass of the substance. The formula is: moles = mass (g) / molar mass (g/mol).
An acid is a substance that donates a proton (H+) in a chemical reaction, while a base is a substance that accepts a proton. Acids have a pH below 7, while bases have a pH above 7.
To balance a chemical equation, you need to make sure that the number of atoms of each element is the same on both sides of the equation. This is achieved by adding coefficients to each compound or element in the equation.