* Gaining electrons: When an atom gains one or more electrons, it becomes negatively charged. This is because electrons carry a negative charge. An atom that gains an electron is called an anion.
* Losing electrons: When an atom loses one or more electrons, it becomes positively charged. This is because the atom now has more protons (positively charged particles) than electrons. An atom that loses an electron is called a cation.
Key points to remember:
* The number of protons in an atom determines its atomic number and its element identity. It remains constant even when an atom gains or loses electrons.
* Electrons are located in the outer shells of an atom and are more easily gained or lost.
* Atoms tend to gain or lose electrons to achieve a stable electron configuration, usually by filling their outermost electron shell.
Example:
* A neutral chlorine atom (Cl) has 17 protons and 17 electrons. It can gain one electron to become a chloride ion (Cl-), which has 17 protons and 18 electrons, giving it a net negative charge of -1.
* A neutral sodium atom (Na) has 11 protons and 11 electrons. It can lose one electron to become a sodium ion (Na+), which has 11 protons and 10 electrons, giving it a net positive charge of +1.
Understanding ionic bonds:
The tendency of atoms to gain or lose electrons to achieve stability is the basis for the formation of ionic bonds. These bonds are formed between oppositely charged ions (cations and anions) and are a major force in the formation of many compounds.
