Understanding Chemistry

Chemistry is at the crux of all matter. Everything in our universe is made up of atoms. The way in which the components of these microscopic building blocks are structured defines the substances they make up, their properties and behaviours and the way in which these elemental chemicals interact with one another to create new forms of matter. Inside the pages of Understanding Chemistry, you will discover how chemical processes shape our modern lives – from fuelling car engines and powering smartphones to creating our favourite alcoholic beverages and washing our hair.…

Everything in the universe is made of countless tiny atoms that are joined into different structures, essentially like toy building blocks. But instead of snapping together through friction, like plastic blocks, atoms snap together through electrical charge. At the centre of every atom you’ll find the nucleus – a blob of positively charged particles called protons and neutrally charged particles called neutrons. The tiny nucleus is surrounded by even smaller negatively charged particles called electrons. Usually, there is an equal number of protons and electrons. Because of their opposite charge, these protons and electrons are attracted to each other, which is what holds the atom together. With this balance, the atom is electrically neutral. But these electrons are a fickle bunch: they’re not only attracted to their own atom’s nucleus…

Electrons Electrons are very small, negatively charged particles that move quickly around the atom’s nucleus. Shells Electrons can only exist in set energy levels, commonly called shells. Each shell has openings for a limited number of electrons. The nucleus The centre of the atom, and almost all of its mass, is the nucleus. The nucleus is made up of protons and neutrons. Protons Protons are positively charged particles in the nucleus. All elements are defined by how many protons they have. Neutrons Neutrons – particles with no electrical charge – help give atoms their mass. They are slightly bigger than protons.…

Atoms don’t follow the rules of Newtonian physics that we see every day in the world around us, making it impossible to visualise what’s actually happening at an atomic level. The best that scientists can do is create theoretical models that give us a general conceptual comprehension of what’s going on. Here are some of the noteworthy models that greatly advanced our atomic understanding… Thomson’s ‘Plum Pudding’ model (1904) English physicist JJ Thomson discovered the electron as far back as 1897, showing for the first time that atoms had smaller constituent components. To account for the atom’s overall neutral charge, Thomson theorised – in his 1904 model – that the negatively charged electrons must sit in a regular pattern within a uniformly distributed positive charge, like raisins in a plum…

Elements are substances made entirely of one type of atom. Each element is defined by how many protons are in a single atom of that element. For example, every hydrogen atom has just one proton, while every gold atom has 79 protons, and so on. In the right circumstances, atoms of different elements can join together to form a chemical compound. The bonds that hold compounds together result from various movements of electrons. Here are two examples: Ionic bond 1 Ionic bond Ionic bonds form when an electron jumps from one atom to another, resulting in two electrically charged atoms, called ions. 2 Valence shell Electrons travel in set energy levels called shells. Each shell has a limited number of openings for electrons. The number of openings in the outermost level,…

Most atoms are highly stable, meaning the nucleus will always hold together, barring extreme circumstances. But in some atoms, the energy that binds the nucleus will eventually fail in a process called radioactive decay – the spontaneous disintegration of the nucleus. The most notorious unstable atoms are elements with a very high number of protons, such as uranium (92 protons). But some lighter elements, eg carbon, can be unstable and radioactive when they have too many or too few neutrons. Neutron-count variations are called isotopes. For example, while garden-variety carbon-12 (six protons and six neutrons) is stable, carbon-14 (six protons and eight neutrons) is radioactive. Radioactive decay results in the ejection of subatomic particles from the nucleus. In alpha radiation, the atom ejects two protons and two neutrons. In beta…