9. Write the atomic notation for a sodium atom

A sodium atom is represented in atomic notation as \( \text{Na}^{23}_{11} \). This notation tells you a couple of cool things: the 23 at the top represents the atomic mass (the sum of protons and neutrons), while the 11 at the bottom shows the atomic number (the number of protons, which also equals the number of electrons in a neutral atom). Sodium loves to hang out in Group 1 of the periodic table, making it super reactive! When you see sodium in nature, it's usually in compound form, like table salt (sodium chloride). Sodium reacts vigorously with water and is essential for life, playing a critical role in nerve function and muscle contractions! However, be careful around it—pure sodium metal can create quite the fireworks show when it encounters moisture!