Final answer:
The periodic table of the elements is a comprehensive list of all known elements, including both metals and nonmetals, and is organized by atomic number. Important elements like hydrogen, oxygen, and nitrogen often exist naturally as diatomic molecules. The periodic table is an indispensable tool for studying the elements in the universe.
Step-by-step explanation:
The periodic table of the elements is a list of all the atoms (those tiny pieces from question 1) that we know of. Atoms are the smallest particles of an element that can still be identified as that element. There are almost 120 known elements, and most are metals, while a smaller number are nonmetals, such as carbon, hydrogen, and oxygen. The periodic table includes 112 officially named elements, and about 118 known elements, with some being man-made. The first 20 elements alongside some common transition metals are displayed in a region of the periodic table, with each element having its unique chemical symbol.
Elements like hydrogen (H₂), nitrogen (N₂), and oxygen (O₂) exist as diatomic molecules in their natural state. These elements are commonly found in the environment and represent a significant portion of the elements in the universe, with hydrogen being the most abundant.
Overall, the periodic table is an essential tool in chemistry, providing a systematic arrangement of elements by atomic number and other chemical properties. It serves as a reference to understand the composition of the universe and the materials that make up everything around us.