Which of the following is formed by an atom that has gained an electron?
ion
covalent bond
new element
neutron
ION!
The correct answer is an ion.
To understand why, let's break down the question and the answer choices:
1. Ion: An ion is formed when an atom gains or loses electrons, resulting in a charged particle. When an atom gains one or more electrons, it becomes negatively charged and is called an anion. So, an atom that has gained an electron is an example of an ion.
2. Covalent bond: A covalent bond is formed by the sharing of electrons between atoms, but it does not involve gaining or losing electrons. Instead, the electrons are shared between the atoms involved, resulting in a stable molecule.
3. New element: Gaining an electron does not create a new element. The number of protons determines the identity of an element, and gaining an electron does not change the number of protons in an atom.
4. Neutron: A neutron is a neutral subatomic particle found in the nucleus of an atom. It has no charge, and gaining an electron would not result in the formation of a neutron.
Therefore, the correct answer is ion. It's important to understand the definitions and properties of different atomic and molecular entities to correctly answer this question.