What element this Bohr model represents?
How many valence electrons this atom has?
Answers
Niels Bohr proposed an early model of the atom as a central nucleus containing protons and neutrons being orbited by electrons in shells. As previously discussed, there is a connection between the number of protons in an element, the atomic number that distinguishes one element from another, and the number of electrons it has. In all electrically-neutral atoms, the number of electrons is the same as the number of protons. Each element, when electrically neutral, has a number of electrons equal to its atomic number.An early model of the atom was developed in 1913 by Danish scientist Niels Bohr (1885–1962). The Bohr model shows the atom as a central nucleus containing protons and neutrons with the electrons in circular orbitals at specific distances from the nucleus.These orbits form electron shells or energy levels, which are a way of visualizing the number of electrons in the various shells. These energy levels are designated by a number and the symbol "n." For example, the 1n shell represents the first energy level located closest to the nucleus.The Bohr model postulated that electron orbited the nucleus in shells of fixed distance.An electron normally exists in the lowest energy shell available, which is the one closest to the nucleus. Energy from a photon of light can bump it up to a higher energy shell, but this situation is unstable and the electron quickly decays back to the ground state.
Bohr Diagrams
Bohr diagrams show electrons orbiting the nucleus of an atom somewhat like planets orbit around the sun. In the Bohr model, electrons are pictured as traveling in circles at different shells, depending on which element you have. contrast the Bohr diagrams for lithium, fluorine and aluminum atoms. The shell closest to the nucleus is called the K shell, next is the L shell, next is the M shell.
Bohr diagrams for neutral lithium, fluorine and aluminum atoms.
Each shell can only hold certain number of electrons. K shell can have 2, L can have 8 , M can have 18 electrons and so on.
Lithium has three electrons:
two go to K shell and
the remaining one goes to the L shell.
Its electronic configuration is K(2), L(1)
Fluorine has nine electrons:
two go to K shell and
the remaining seven go to the L shell.
Its electronic configuration is K(2), L(7). Note that L can have 8 electrons.
Aluminum has thirteen electrons:
two go to the K shell,
eight go to the L shell, and
remaining three go to the M shell.
Its electronic configuration is K(2), L(8), M(3). Note that the M shell can have 18 electrons.