📝 The Structure of an atom

Task

🎧️ Listen to the recording and mind pronunciation of words.

Every atom has nearly all its mass concentrated in a tiny region called the nucleus. The nucleus is made up of particles called nucleons. There are two types of nucleon: protons and neutrons. Atoms of different elements have different numbers of protons. Outside the nucleus, particles called electrons move around in regions of space called orbitals. Chemists often find it convenient to use a model of the atom in which electrons move around the nucleus in electron shells. Each shell is a certain distance from the nucleus at its own particular energy level. In a neutral atom, the number of electrons is equal to the number of protons. Every atom of the same element has the same number of protons in its nucleus. The nucleon number is the number of protons plus neutrons in the nucleus of an atom. This is also known as the mass number. Number of neutrons = nucleon number – number of protons. Atoms of the same element that have differing numbers of neutrons are called isotopes. Isotopes of a particular element have the same chemical properties because they have the same number of electrons. They have slightly different physical properties, such as small differences in density.

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