Diamagnetic materials such as water, nitrogen, copper, calcium carbonates are slightly repelled by a magnetic field if they are placed between poles of a magnet. They are not attracted by such a magnetic field. Diamagnetism is a very weak interaction of all material with a magnetic field.
All materials exhibit diamagnetism, but some materials have other intrinsic but stronger magnetic properties than diamagnetism. As a result, they are classified according to the stronger magnetic properties.
If a material is attracted into a magnetic field when placed between magnetic poles, the material is said to be paramagnetic. A paramagnetism material has unpaired electrons in the molecular or atomic orbitals.
When atoms of an element have unpaired electrons, the element will be paramagnetic. For example, the electronic configuration of Co is [Ar]4s2 3d7, and 3 of the 7 d electrons are unpaired. You would expect Co to exhibit paramagnetism.
Iron, Fe, with electronic configuration [Ar]4s2 3d7, is a typical ferromagnetic material. Iron is greatly attracted by magnets. The "tinny magnets" of the atoms align themselves to enhance each other in ferromagnetic material. The aligned tinny magnets are called magnetic domains.
Diamagnetis is exhibited by all materials, including paramagnetic and ferromagnetic materials. But paramagnetism and ferromagnetism overpower the diamagnetism.
Apply the same reasoning to figure out trends for elements in the periodic table.
Note the trend of the first IE, or 2nd IE in periods and in groups. Generally speaking, the IE is the highest for the lightest element. In terms of IE, the order for the first group is:
Electron affinity (EA) is the energy or enthalpy given off when a species acquires an electron:
The most electronegative element, F, releases -322 kJ/mol whereas chlorine, Cl, releases the most energy when it acquires an electron, -348.7 kJ/mol. For some unknown reasons, the electron affinity for chlorine is larger than that of fluorine.
If you reverse the above reaction, it looks like the ionization of the negative ion. Thus, the negative of EA is the zeroth ionization energy (0th IE) of the neutral atom, Cl in this case.
IE and EA are quantities of energy when an electron is removed from or added to an atom. They convey no information regarding the bonding electrons between atoms. Pauling invented the concept called electronegativity to indicate the degree of attraction of bonding electrons. Electronegativity is a scale based on information of IE, EA, bondlength and bond energy. Many schalors have used different methods to evaluate electronegativity, and Pauling's scale is the most common one in text books.
Electronegativity of some elements are given below for your reference:
B C N O F 2.0 2.6 3.0 3.4 4.0 Cs Si P S Cl Kr Xe 0.8 1.9 2.2 2.6 3.2 2.9 2.6The higher the electronegativity, the more attraction the element has towards bonding electrons. Bonding between two elements with large electronegativity difference tends to be ionic. It is interesting to note that inert gases Kr and Xe have elenegativities similar to those of nitrogen and carbon.
On the periodic table, there is a general trend. An element close to F has a large electronegativity, whereas an element close to Cs on the opposit corner of the periodic table from F has the least electronegativity.
The periodic table is a convenient way to correlate chemical properties. For example, from their position on the periodic table, we easily recognize them as metals, semimetals (metalloids), or nonmetals.
Most elements are metals (M), some are metalloids (o), nonmetals (-), and inert gases (i), on the top right hand of the long periodic table.
- i Mo o----i MM oo---i MM MMMMMMMMMMMoo--i MMMMMMMMMMMMMMMMMMMMMMMMMMMMoo-i MMMMMMMMMMMMMMMMMMMMMMMMMMMMMooiLook at some metals, and see if you can describe their characteristics. If not, please check some resource books to see if they give a description you like?
Metals are characterized by having high melting point, high electric and heat conductivity, metallic bonding, malleable, ductile, form positive ions Cu2+, Fe3+, and form alloys with one another. Check out a metal, and you'll be amazed how close it has come to your life.
Nonmetals have low melting points, form molecules, atoms in their solids are covalently bonded. They are poor conductors of heat and electricity, and they form negative ions or form molecular compounds. Here are some non-metals. Note however, that diamond is an exceptionally good heat conductor, but it does not conduct electricity.
The chemistry of these elements is best discussed in GROUPS such as alkali metals, carbon group, halogens, inert gases, etc.
Explain what is diamagnetism and how this type of material behave in a magnetic field.
Paramagnetism is due to unpaird electrons in the material.
Explain what is ionization energy, and describe the trend for a group of element.
It takes the most energy to remove an electron from Li in this group. Which of the inert gase has the highest IE, He, Ne, Ar, Kr, or Rn?
The electron affinity are given below:
Cs C O Cl F -45.5 -122 -141 -349 -322 kJ/mol
You should know that F is the most electronegative element, and Cs is the least electronegative. Francium should be, but there is no natural occuring francium because its isotopes are all radioactive.
Due to the large electronegativity and the small size of oxygen atoms, oxygen compounds such as water and ethanol form hydrogen bonds.