The Atom As A Nucleus With Orbital Electrons

The Atom As A Nucleus With Orbital Electrons - Atomic structure and the periodic table

Chemistry Explain provide notes about Atomic structure and the periodic table today we discuss “The Atom As A Nucleus With Orbital Electrons” Inorganic Chemistry

All atoms contain a central nucleus surrounded by one or more orbital electrons. The nucleus always contains protons and every one nucleus heavier than hydrogen contains neutrons too. the protons and neutrons together make up most of the mass of the atom. Both protons and neutrons are particles of unit mass, but a proton has one positive charge and a neutron is electrically neutral (i.e. carries no charge). Thus the nucleus is always positively charged. The number of positive charges on the nucleus is exactly balanced by an equal number of orbital electrons, each of which carries one negative charge. Electrons arc relatively light -'- about I /1836 the mass of a proton. The 103 or so Clements at present known are all built up from these three fundamental particles in a simple way.

Hydrogen is the first and most simple elements It consists of a nucleus containing one proton and therefore has one positive charge, which is balanced by one negatively charged orbital electron. the second element is helium. The nucleus contains two protons, and so has a charge of +2. The nuclear charge of +2 is balanced by two negatively charged orbital electrons. The nucleus also contains two neutrons, which minimize the repulsion between the protons in the nucleus and increase the mass of the atom. All nuclei heavier than hydrogen contain neutrons, but the amount present can't be predicted reliably.

This pattern is repeated for the rest of the elements. Element 3, lithium, has three protons in the nucleus (plus some neutrons). The nuclear charge is +3 and is balanced by three orbital electrons. Element 103, lawrencium, has 103 protons in the nucleus (plus some neutrons). The nuclear charge is · + 103 and is balanced by 103 orbital electrons. The number of positive charges on the nucleus of an atom always equals the number of orbital electrons and is named the atomic number of the element. In the simple planetary theory of the town, we imagine that these electrons move around the nucleus in circular orbits, in much the same way as the planets orbit around the sun. Thus hydrogen and helium (Figure I. I) have one anti two electrons respectively in their first orbit. The first orbit is then full. The next eight atoms are lithium, beryllium, boron, carbon,




This pattern is repeated for the rest of the elements. Element 3, lithium, has three protons in the nucleus (plus some neutrons). The nuclear charge is +3 and is balanced by three orbital electrons. Element 103, lawrencium, has 103 protons in the nucleus (plus some neutrons). The nuclear charge is · + 103 and is balanced by 103 orbital electrons. The number of positive charges on the nucleus of an atom always equals the number of orbital electrons and is called the atomic number of the element. In the simple planetary theory of the town, we imagine that these electrons move around the nucleus in circular orbits, in much the same way as the planets orbit around the sun. Thus hydrogen and helium (Figure I. I) have one anti two electrons respectively in their first orbit. The first orbit is then full. The next eight atoms are lithium, beryllium, boron, carbon.

nitrogen, oxygen, fluorine, and neon. Each has another proton within the nucleus. the preceding element and the extra electrons go into a second orbit (Figure 1.2). This orbit is then full. In the next eight elements (with atomic numbers 11 to 18), the additiOnal electrons enter the third shell. The charged electrons are interested in the positive nucleus by electrostatic attraction. An electron near the nucleus is strongly attracted by the nucleus and has low potential energy. An electron distant from the nucleus is less firmly held and has high potential energy.