Unit 4

Front

What is a physical change?

Back

A physical change is a change that affects one or more physical properties of a substance without altering its chemical composition. Examples include changes in state (solid, liquid, gas), shape, or size.

Front

What is a chemical change?

Back

A chemical change is a change that results in the formation of new chemical substances. It involves the breaking and forming of bonds between atoms. Indicators include color change, gas production, and precipitate formation.

Front

What is the significance of balancing chemical equations?

Back

Balancing chemical equations is essential to obey the law of conservation of mass, which states that matter cannot be created or destroyed in a chemical reaction. It ensures that the number of atoms for each element is the same on both sides of the equation.

Front

What is a half-reaction in redox reactions?

Back

A half-reaction is either the oxidation or reduction part of a redox reaction, showing the transfer of electrons. Oxidation involves loss of electrons, while reduction involves gain of electrons.

Front

What is a precipitate?

Back

A precipitate is an insoluble solid that forms when two solutions are mixed and a chemical reaction occurs, resulting in a new compound.

Front

What is the role of coefficients in a balanced chemical equation?

Back

Coefficients indicate the number of moles of each substance involved in the reaction. They are used to balance the equation according to the law of conservation of mass.

Front

What is the photoelectron spectrum?

Back

The photoelectron spectrum is a graph that shows the energies of electrons ejected from an atom when it is exposed to ultraviolet or X-ray radiation. It provides information about the electron configuration of the atom.

Front

What is the electron configuration for an atom?

Back

The electron configuration is the distribution of electrons among the various orbitals of an atom. It is represented by a series of numbers and letters indicating the energy levels and types of orbitals.

Front

What is the difference between an ionic and covalent bond?

Back

An ionic bond is formed when electrons are transferred from one atom to another, resulting in the formation of charged ions. A covalent bond is formed when two atoms share electrons.

Front

What is the concept of molarity?

Back

Molarity is a measure of concentration, defined as the number of moles of solute per liter of solution. It is expressed in moles per liter (mol/L).