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# Chapter 4: Structure of an atom It is very difficult to imagine anything as small as an atom. 100 million of them side by side would only measure about 1 cm across. Despite this, scientists have been able to find out a great deal about atoms. Scientists currently believe that an atom consists of...

# Chapter 4: Structure of an atom It is very difficult to imagine anything as small as an atom. 100 million of them side by side would only measure about 1 cm across. Despite this, scientists have been able to find out a great deal about atoms. Scientists currently believe that an atom consists of a dense nucleus surrounded by a cloud of negatively charged electrons. The nucleus contains positively charged protons and electrically neutral neutrons. The number of electrons in an atom is always the same as the number of protons, so atoms are overall electrically neutral. The image shows a theoretical structure of an atom. The atom consists of a central nucleus surrounded by a cloud of negatively charged electrons, marked by dark blue circles containing smaller positive charges. The nucleus is also positively charged, marked by two yellow circled charges. The dark blue circle is labeled 'negative electron' and the yellow circle is labeled 'positive charged nucleous'.