Question

Complete the following paragraph about elements and compounds:

a) Elements are simple substances made of the same type of atoms. They cannot be broken down chemically. There are about 118 known elements, and most elements are pure. They are diverse in appearance and are good conductors of heat and electricity.
b) Elements are simple compounds made of the same type of molecules. They cannot be broken down chemically. There are about 118 known elements, and most elements are complex. They are similar in appearance and are good insulators of heat and electriciy.
c) Elements are simple substances made of the same type of particles. They cannot be broken down chemically. There are about 118 known elements, and most elements are solids. They are uniform in appearance and are good insulators of heat and conductors of electricity.
d) Elements are simple substances made of the same type of atoms. They cannot be broken down chemically. There are about 118 known elements, and most elements are mixtures. They are distinct in appearance and are good insulators of heat and conductors of electricity.

Answer 1

Elements are simple substances that cannot be chemically broken down into simpler substances and there are 118 known elements. Compounds are made up of more than one type of atom and there are tens of millions of different compounds.

Step-by-step explanation:

The correct completion for the paragraph about elements and compounds is option (a). Elements are simple substances made of the same type of atoms. They cannot be broken down chemically into simpler substances. Currently, there are about 118 known elements, most of which are pure substances. Elements are found naturally and can vastly differ in appearance, with properties suitable for conducting heat and electricity due to the movement of free electrons in their atomic structures.

Contrary to elements, compounds consist of two or more different types of atoms chemically bonded together. An example of a compound is water (H₂O), which is made up of hydrogen and oxygen atoms. Compounds have different properties than the separate elements that they consist of. Because they are formed by a chemical reaction, compounds can be broken down into simpler substances by chemical means. Scientists have discovered tens of millions of different compounds to date.