What kind of arrangement of electrons in the outer orbit

Chlorine has 7 electrons in its valence shell. To meet the octet rule, it must either gain one electron or lose seven electrons. Gaining one is easier than losing seven so it will gain one electron to have a total of eight electrons when it forms an ion i.

Allison Soult , Ph. Department of Chemistry, University of Kentucky. Learning Outcomes Determine the energy levels of electrons for the first 20 elements. Explain the relevance of valence electrons in chemical processes.

Identify the number of valence electrons in an element. Describe the stability of an atom as a result of following the octet rule.

Electron Arrangement Electrons are not randomly arranged in an atom and their position within the atom can be described using electron arrangements , which are a simplified version of electron configurations. Solution Oxygen has eight electrons. Solution Chlorine has 17 electrons. How many valence electrons does it have? Sodium atoms have 11 electrons. Two of these are in the lowest energy level, eight are in the second energy level and then one electron is in the third energy level.

This is a very unstable arrangement, and the element sodium is a highly reactive, deadly white semi-solid that will burst into flames on exposure to the air or will burn through human flesh on contact. A reactive substance. Chlorine atoms have 17 electrons. Two in the lowest, eight in the second and 7 in the third energy level.

This too is a very unstable arrangement. This element is a gas at room temperature and was used in World War One as a poisonous attack weapon because of its high reactivity with human lungs.

These two atoms were made for one another. Sodium atoms readily give up the single electron in the outermost orbital. This electron is immediately picked up by a chlorine atom and fitted into the last empty space in its outermost orbital. Now both atomic arrangements are much more stable.

They both have outermost orbitals which are filled with electrons. However, there is a price to be paid for this stability. In giving up an electron, the sodium atom has lost a negative electrical charge. The valence shell is shell 2 and contains 8 valence electrons. Thus the number of nonvalence electrons is 2 10 total electrons — 8 valence. The atomic number for neon is 10, therefore:.

Flourine has 9 electrons but F — has gained an electron and thus has The electron configuration is the same as for neon and the number of nonvalence electrons is 2.

The atomic number for F — is 9, therefore:. Diamagnetic atoms have only paired electrons, whereas paramagnetic atoms, which can be made magnetic, have at least one unpaired electron.

Note that the poles of the magnets are aligned vertically and alternate two with north facing up, and two with south facing up, diagonally. Any time two electrons share the same orbital, their spin quantum numbers have to be different. This is important when it comes to determining the total spin in an electron orbital.

In order to decide whether electron spins cancel, add their spin quantum numbers together. Whenever two electrons are paired together in an orbital, or their total spin is 0, they are called diamagnetic electrons. Think of spins as clockwise and counterclockwise. If one spin is clockwise and the other is counterclockwise, then the two spin directions balance each other out and there is no leftover rotation.

Note what all of this means in terms of electrons sharing an orbital: Since electrons in the same orbital always have opposite values for their spin quantum numbers m s , they will always end up canceling each other out.

In other words, there is no leftover spin in an orbital that contains two electrons. Electron spin is very important in determining the magnetic properties of an atom. If all of the electrons in an atom are paired up and share their orbital with another electron, then the total spin in each orbital is zero and the atom is diamagnetic.

Diamagnetic atoms are not attracted to a magnetic field, but rather are slightly repelled. Electrons that are alone in an orbital are called paramagnetic electrons. Remember that if an electron is alone in an orbital, the orbital has a net spin, because the spin of the lone electron does not get canceled out. If even one orbital has a net spin, the entire atom will have a net spin. Therefore, an atom is considered to be paramagnetic when it contains at least one paramagnetic electron. In other words, an atom could have 10 paired diamagnetic electrons, but as long as it also has one unpaired paramagnetic electron, it is still considered a paramagnetic atom.

Just as diamagnetic atoms are slightly repelled from a magnetic field, paramagnetic atoms are slightly attracted to a magnetic field. Paramagnetic properties are due to the realignment of the electron paths caused by the external magnetic field. Paramagnets do not retain any magnetization in the absence of an externally applied magnetic field, because thermal motion randomizes the spin orientations.

Stronger magnetic effects are typically only observed when d- or f-electrons are involved. The size of the magnetic moment on a lanthanide atom can be quite large, as it can carry up to seven unpaired electrons, in the case of gadolinium III hence its use in MRI. Privacy Policy. Skip to main content. Periodic Properties. Search for:. Learning Objectives Determine the electron configuration for elements and ions, identifying the relation between electron shells and subshells.

Key Takeaways Key Points If the energy of an atom is increased, an electron in the atom gets excited. To go back to its ground state, the electron releases energy. The energy of the light released when an electron drops in energy level is the same as the difference in energy between the two levels. Electrons closest to the nucleus will have the lowest energy.

In a more realistic model, electrons move in atomic orbitals, or subshells. There are four different orbital shapes: s, p, d, and f.

Within each shell, the s subshell is at a lower energy than the p. There are guidelines for determining the electron configuration of an atom. An electron will move to the orbital with lowest energy. Each orbital can hold only one electron pair. Electrons will separate as much as possible within a shell.

Key Terms frequency : The number of occurrences of a repeating event per unit of time. Learning Objectives Write electron configurations for elements in standard notation.

Key Takeaways Key Points The Madelung rule defines the order in which atomic orbitals are filled with electrons. Electrons fill orbitals starting at the lowest available energy state before filling higher states. Aufbau procedure: Determine number of electrons for the atom of interest. Fill available orbitals starting with the lowest-energy levels first and avoid pairing electrons in a single orbital until it is necessary.

Electron configuration notation describes the energy levels, orbitals, and the number of electron. The number and letter describe the energy level and orbital respectively, and the superscript number shows how many electrons are in that orbital. The Aufbau principle works well for the first 18 elements but then becomes less useful. Key Terms Pauli Exclusion Principle : The quantum mechanical principle that no two identical fermions particles with half-integer spin may occupy the same quantum state simultaneously.

Electrons arrange themselves in order to minimize their interaction energy. They will always occupy an empty orbital before they pair up to minimize repulsion. Unpaired electrons have the same spins because they meet less often if traveling in the same direction than if traveling in opposite directions. An atom is most reactive when its valence shell is not full and most stable when its valence orbitals are full. Elements that have the same number of valence electrons often have similar properties.

Key Terms repulsion : A force that moves two bodies away from each other. The Shielding Effect and Effective Nuclear Charge The shielding effect, approximated by the effective nuclear charge, is due to inner electrons shielding valence electrons from the nucleus.

Learning Objectives Calculate effective nuclear charges experienced by valence electrons. Key Takeaways Key Points The shielding effect describes the balance between the pull of the protons on valence electrons and the repulsion forces from inner electrons. The shielding effect explains why valence-shell electrons are more easily removed from the atom.

The effect also explains atomic size. The more shielding, the further the valence shell can spread out and the bigger atoms will be. The effective nuclear charge is the net positive charge experienced by valence electrons.