Read and complete the text about chemistry using the words in the box. bind charge science
nucleus interactions shape
mass particles matter
density substances amounts
ions molecules

Chemistry is the science that systematically studies the composition, properties
and activity of and various elementary forms of .
Chemistry is the study of matter and energy and interactions between them.
Energy has no or form. Matter is everything that occupies space and has
. refers to the amount of matter in a given amount of
space and is defined as the mass per unit of a substance.
The fundamental building block of matter is the atom. It has a at its
centre consisting of protons, which have a positive electrical , and neutrons
which are uncharged. Negatively charged electrons circle around nuclei. There are
super-small inside the protons and neutrons called quarks.
Chemical reactions involve between the electrons of one atom
and the electrons of another atom. Atoms which have different of
electrons and protons have positive or negative electrical charge and are called
. When atoms together, they can make larger building blocks of
matter called

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