Question

2.3 elements and compounds

1. how could you distinguish an element from a compound?

Explanation:

An element is a pure substance made of only one type of atom (e.g., hydrogen, \(H\); oxygen, \(O\)). A compound is a pure substance made of two or more different elements chemically bonded in a fixed ratio (e.g., water, \(H_2O\); carbon dioxide, \(CO_2\)). To distinguish them, we can check if the substance can be broken down into simpler substances by chemical means: elements cannot be broken down into simpler substances by chemical reactions (they are the simplest form of matter), while compounds can be broken down into their constituent elements (e.g., \(H_2O\) can be broken into \(H_2\) and \(O_2\) via electrolysis). Also, looking at the chemical formula: an element has a formula with only one type of atom (e.g., \(Fe\), \(N_2\)), a compound has a formula with multiple types of atoms (e.g., \(NaCl\), \(C_6H_{12}O_6\)).

Answer:

To distinguish an element from a compound:

1. Chemical Decomposition: An element cannot be broken down into simpler substances by chemical reactions (it is the simplest form of matter, made of one type of atom). A compound can be broken down into its constituent elements (e.g., \(H_2O\) (compound) decomposes into \(H_2\) and \(O_2\) (elements) via electrolysis).
2. Chemical Formula: An element’s formula contains only one type of atom (e.g., \(Fe\), \(O_2\), \(Au\)). A compound’s formula contains two or more different atoms in a fixed ratio (e.g., \(CO_2\) (C and O), \(NaCl\) (Na and Cl)).