Chemically, hydrogen, carbon, nitrogen, oxygen, phosphorus, arsenic and selenium are the non-metallic elements in the periodic table.

Seventeen elements are generally classified as nonmetals; most are gases (hydrogen, helium, nitrogen, oxygen, fluorine, neon, chlorine, argon, krypton, xenon and radon); one is a liquid (bromine); and a few are solids (carbon, phosphorus, sulfur, selenium, and iodine).

So, if we include the nonmetals group, halogens, and noble gases, all of the elements that are nonmetals are:

• Hydrogen (sometimes)
• Carbon.
• Nitrogen.
• Oxygen.
• Phosphorus.
• Sulfur.
• Selenium.
• Fluorine.

Carbon is a solid non-metal element. Pure carbon can exist in very different forms. The most common two are diamond and graphite….Diamond and graphite.

Fluorine

Fluorine is the most electronegative element because it has 5 electrons in it’s 2P shell. The optimal electron configuration of the 2P orbital contains 6 electrons, so since Fluorine is so close to ideal electron configuration, the electrons are held very tightly to the nucleus.

Question 2. On the Pauling scale the electronegativity of nitrogen and oxygen are respectively 3.0 and 3.5. Oxygen has 8 protons in the nucleus while nitrogen only has 7. A bonding pair will experience more attraction from the oxygen’s nucleus than from nitrogen’s, and so the electronegativity of oxygen is greater.

Fluorine. D. Oxygen. Hint: We should remember that the element which will release the most amount of energy on adding an electron in its isolated gaseous atom will posse’s highest electron affinity in the periodic table.

mercury

The first electron affinity is the energy released when 1 mole of gaseous atoms each acquire an electron to form 1 mole of gaseous -1 ions. It is the energy released (per mole of X) when this change happens. First electron affinities have negative values.

What is the trend for electron affinity? Electron affinity increases upward across periods of a periodic table for the groups and from left to right, because the electrons added to the energy levels get closer to the nucleus, making the nucleus and its electrons more attractive.

Electron affinity is the energy change that results from adding an electron to a gaseous atom. For example, when a fluorine atom in the gaseous state gains an electron to form F⁻(g), the associated energy change is -328 kJ/mol.

Thus, in case of noble gases, where it resists the addition of electrons, extra energy is required in order to force the electron to bind to the stable atom. Therefore, making the electron gain enthalpies positive. Its tendency to accept the electron from neon to radon increases, making it less positive down the group.

Various factors that affect electron affinity are atomic size, nuclear charge and the symmetry of the electronic configuration. Atomic size: With increase in the atomic size, the distance between the nucleus and the incoming electron also increases.

Third in importance for bond formation after size and ionization energy is the energy change accompanying the attachment of electrons to a neutral atom. This energy is expressed as the electron affinity, which is the energy released when an electron is attached to an atom of the element.

The electron affinity is defined as the energy change that occurs when an atom gains an electron, releasing energy in the process. If a reaction is exothermic, the change in energy is negative. This means that the electron affinity is positive.

Chlorine

When electrons are added to an atom, the increased negative charge puts stress on the electrons already there, causing energy to be released. When electrons are removed from an atom, that process requires energy to pull the electron away from the nucleus.

Large atoms have low ionization energy and low electron affinity. Therefore, they tend to lose electrons and do not tend to gain electrons. Any electrons added to a noble gas would have to be the first electron in a new (larger) energy level. This causes the noble gases to have essentially zero electron affinity.

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Exothermic vs endothermic process When an electron is added to an atom, the energy change is exothermic because of the attraction of the electron to the nucleus. Therefore, this process will be endothermic, as opposed to EA1.