The elements in the periodic table are organized into groups based on their similar chemical properties and electronic configurations. The number of element groups is determined by the columns in the periodic table. Each column represents a group, and the elements within a group share similar characteristics. There are 18 columns or groups in the periodic table labeled from 1 to 18. The elements in the same group have the same number of electrons in their outermost electron shell, which contributes to their similar chemical behavior. The division into groups helps in understanding and predicting the chemical behavior of elements. So, when the question mentions "element groups," it is referring to these 18 columns in the periodic table.

Dimitri Mendeleev is credited as the creator of the periodic table. He was a Russian chemist who organized the elements based on their atomic weight and properties. Mendeleev's periodic table arranged the elements in rows and columns, leaving gaps for undiscovered elements and predicting their properties. His work laid the foundation for the modern periodic table that we use today.

The symbol Au represents the element gold in the periodic table. Chemical elements are often represented by one or two-letter symbols, and in this case, Au is derived from the Latin word "aurum," which means gold. Each element has a unique symbol to simplify communication in the field of chemistry. Therefore, when you see the symbol Au, it specifically refers to the metallic element gold with its distinct properties and characteristics.

The atomic number of an element is the number of protons found in the nucleus of its atoms. For helium, the atomic number is 2, which means each helium atom has two protons. The atomic number determines the element's identity and its position on the periodic table. Helium, with an atomic number of 2, is a noble gas, making it very stable and non-reactive. It is the second element on the periodic table, following hydrogen. Understanding atomic numbers helps in identifying elements and predicting their chemical behavior based on their position in the periodic table.

The symbol Sn represents the element tin in the periodic table. Chemical symbols are standardized abbreviations used to represent elements, and they are often derived from the element's name in English, Latin, or another language. In the case of tin, the symbol Sn is based on the Latin word "stannum." So, whenever you see the symbol Sn, it specifically denotes the element tin with its unique properties and characteristics.