Although affinity varies greatly across the periodic table, some patterns emerge. Generally, the elements on the right side of the periodic table will have large negative electron affinity. The electron affinities will become less negative as you go from the top to the bottom of the periodic table. However, nitrogen, oxygen, and fluorine do not follow this trend. Moreover, nonmetals have more positive affinity than metals. Atoms whose anions are more stable than neutral atoms have a greater affinity.
Chlorine most strongly attracts extra electrons, while neon most weakly attracts an extra electron. The higher the associated electronegativity number, the more an element or compound attracts electrons towards it. The most electronegative atom, fluorine, is assigned a value of 4.
Electronegativity is related with ionization energy and electron affinity. Electrons with low ionization energies have low electronegativities because their nuclei do not exert a strong attractive force on electrons.
Elements with high ionization energies have high electronegativities due to the strong pull exerted by the positive nucleus on the negative electrons.
Therefore the electronegativity is greatest at the top-right of the periodic table and decreases toward the bottom-left. Ionization energy , also called ionization potential , is the energy necessary to remove an electron from the neutral atom. A Chlorine atom, for example, requires the following ionization energy to remove the outermost electron.
The ionization energy associated with removal of the first electron is most commonly used. The n th ionization energy refers to the amount of energy required to remove an electron from the species with a charge of n There is an ionization energy for each successive electron removed. The electrons that circle the nucleus move in fairly well-defined orbits.
Some of these electrons are more tightly bound in the atom than others. For example, only 7. Helps to understand reactivity of elements especially metals, which lose electrons. In general, the ionization energy increases moving up a group and moving left to right across a period.
Ionization energy is is related with electronegativity and electron affinity. In general, boiling is a phase change of a substance from the liquid to the gas phase. The boiling point of a substance is the temperature at which this phase change boiling or vaporization occurs.
The temperature at which vaporization boiling starts to occur for a given pressure is also known as the saturation temperature and at this conditions a mixture of vapor and liquid can exist together. The liquid can be said to be saturated with thermal energy.
Any addition of thermal energy results in a phase transition. At the boiling point the two phases of a substance, liquid and vapor, have identical free energies and therefore are equally likely to exist.
Below the boiling point, the liquid is the more stable state of the two, whereas above the gaseous form is preferred. The pressure at which vaporization boiling starts to occur for a given temperature is called the saturation pressure.
When considered as the temperature of the reverse change from vapor to liquid, it is referred to as the condensation point. As can be seen, the boiling point of a liquid varies depending upon the surrounding environmental pressure. A liquid in a partial vacuum has a lower boiling point than when that liquid is at atmospheric pressure. A liquid at high pressure has a higher boiling point than when that liquid is at atmospheric pressure. In the periodic table of elements , the element with the lowest boiling point is helium.
Both the boiling points of rhenium and tungsten exceed K at standard pressure. Since it is difficult to measure extreme temperatures precisely without bias, both have been cited in the literature as having the higher boiling point. In general, melting is a phase change of a substance from the solid to the liquid phase. The melting point of a substance is the temperature at which this phase change occurs. The melting point also defines a condition in which the solid and liquid can exist in equilibrium.
Adding a heat will convert the solid into a liquid with no temperature change. At the melting point the two phases of a substance, liquid and vapor, have identical free energies and therefore are equally likely to exist. Below the melting point, the solid is the more stable state of the two, whereas above the liquid form is preferred. The melting point of a substance depends on pressure and is usually specified at standard pressure.
When considered as the temperature of the reverse change from liquid to solid, it is referred to as the freezing point or crystallization point. See also: Melting Point Depression. The first theory explaining mechanism of melting in the bulk was proposed by Lindemann, who used vibration of atoms in the crystal to explain the melting transition. Solids are similar to liquids in that both are condensed states, with particles that are far closer together than those of a gas.
The atoms in a solid are tightly bound to each other, either in a regular geometric lattice crystalline solids, which include metals and ordinary ice or irregularly an amorphous solid such as common window glass , and are typically low in energy. The motion of individual atoms , ions, or molecules in a solid is restricted to vibrational motion about a fixed point.
As a solid is heated, its particles vibrate more rapidly as the solid absorbs kinetic energy. At some point the amplitude of vibration becomes so large that the atoms start to invade the space of their nearest neighbors and disturb them and the melting process initiates.
The melting point is the temperature at which the disruptive vibrations of the particles of the solid overcome the attractive forces operating within the solid.
As with boiling points, the melting point of a solid is dependent on the strength of those attractive forces. For example, sodium chloride NaCl is an ionic compound that consists of a multitude of strong ionic bonds. On the other hand, ice solid H 2 O is a molecular compound whose molecules are held together by hydrogen bonds, which is effectively a strong example of an interaction between two permanent dipoles.
Though hydrogen bonds are the strongest of the intermolecular forces, the strength of hydrogen bonds is much less than that of ionic bonds. Covalent bonds often result in the formation of small collections of better-connected atoms called molecules, which in solids and liquids are bound to other molecules by forces that are often much weaker than the covalent bonds that hold the molecules internally together. Such weak intermolecular bonds give organic molecular substances, such as waxes and oils, their soft bulk character, and their low melting points in liquids, molecules must cease most structured or oriented contact with each other.
The thermal conductivity of most liquids and solids varies with temperature. For vapors, it also depends upon pressure. In general:. When electrons and phonons carry thermal energy leading to conduction heat transfer in a solid, the thermal conductivity may be expressed as:. Metals are solids and as such they possess crystalline structure where the ions nuclei with their surrounding shells of core electrons occupy translationally equivalent positions in the crystal lattice.
Metals in general have high electrical conductivity , high thermal conductivity , and high density. Accordingly, transport of thermal energy may be due to two effects:. The unique feature of metals as far as their structure is concerned is the presence of charge carriers, specifically electrons. The electrical and thermal conductivities of metals originate from the fact that their outer electrons are delocalized.
Their contribution to the thermal conductivity is referred to as the electronic thermal conductivity, k e. In fact, in pure metals such as gold, silver, copper, and aluminum, the heat current associated with the flow of electrons by far exceeds a small contribution due to the flow of phonons. In contrast, for alloys, the contribution of k ph to k is no longer negligible. For nonmetallic solids , k is determined primarily by k ph , which increases as the frequency of interactions between the atoms and the lattice decreases.
In fact, lattice thermal conduction is the dominant thermal conduction mechanism in nonmetals, if not the only one. In solids, atoms vibrate about their equilibrium positions crystal lattice. The vibrations of atoms are not independent of each other, but are rather strongly coupled with neighboring atoms.
The regularity of the lattice arrangement has an important effect on k ph , with crystalline well-ordered materials like quartz having a higher thermal conductivity than amorphous materials like glass.
Phonons play a major role in many of the physical properties of condensed matter, like thermal conductivity and electrical conductivity. In fact, for crystalline, nonmetallic solids such as diamond, k ph can be quite large, exceeding values of k associated with good conductors, such as aluminum. K of any bulk material. In physics, a fluid is a substance that continually deforms flows under an applied shear stress.
Fluids are a subset of the phases of matter and include liquids , gases , plasmas and, to some extent, plastic solids. Because the intermolecular spacing is much larger and the motion of the molecules is more random for the fluid state than for the solid state, thermal energy transport is less effective.
The thermal conductivity of gases and liquids is therefore generally smaller than that of solids. In liquids, the thermal conduction is caused by atomic or molecular diffusion. In gases, the thermal conduction is caused by diffusion of molecules from higher energy level to the lower level. The effect of temperature, pressure, and chemical species on the thermal conductivity of a gas may be explained in terms of the kinetic theory of gases.
Air and other gases are generally good insulators, in the absence of convection. Therefore, many insulating materials e. Alternation of gas pocket and solid material causes that the heat must be transferred through many interfaces causing rapid decrease in heat transfer coefficient. The thermal conductivity of gases is directly proportional to the density of the gas, the mean molecular speed, and especially to the mean free path of molecule. The mean free path also depends on the diameter of the molecule, with larger molecules more likely to experience collisions than small molecules, which is the average distance traveled by an energy carrier a molecule before experiencing a collision.
Light gases, such as hydrogen and helium typically have high thermal conductivity. Dense gases such as xenon and dichlorodifluoromethane have low thermal conductivity. As was written, in liquids, the thermal conduction is caused by atomic or molecular diffusion, but physical mechanisms for explaining the thermal conductivity of liquids are not well understood.
Liquids tend to have better thermal conductivity than gases, and the ability to flow makes a liquid suitable for removing excess heat from mechanical components. The heat can be removed by channeling the liquid through a heat exchanger. The coolants used in nuclear reactors include water or liquid metals, such as sodium or lead. Thermal expansion is generally the tendency of matter to change its dimensions in response to a change in temperature. It is usually expressed as a fractional change in length or volume per unit temperature change.
Thermal expansion is common for solids, liquids and for gases. Unlike gases or liquids, solid materials tend to keep their shape when undergoing thermal expansion. A linear expansion coefficient is usually employed in describing the expansion of a solid, while a volume expansion coefficient is more useful for a liquid or a gas.
The volumetric thermal expansion coefficient is the most basic thermal expansion coefficient, and the most relevant for fluids. In general, substances expand or contract when their temperature changes, with expansion or contraction occurring in all directions. In a solid or liquid, there is a dynamic balance between the cohesive forces holding the atoms or molecules together and the conditions created by temperature.
Therefore higher temperatures imply greater distance between atoms. Different materials have different bonding forces and therefore different expansion coefficients. If a crystalline solid is isometric has the same structural configuration throughout , the expansion will be uniform in all dimensions of the crystal. If it is not isometric, there may be different expansion coefficients for different crystallographic directions, and the crystal will change shape as the temperature changes.
Specific heat, or specific heat capacity, is a property related to internal energy that is very important in thermodynamics. The intensive properties c v and c p are defined for pure, simple compressible substances as partial derivatives of the internal energy u T, v and enthalpy h T, p , respectively:. The properties c v and c p are referred to as specific heats or heat capacities because under certain special conditions they relate the temperature change of a system to the amount of energy added by heat transfer.
Different substances are affected to different magnitudes by the addition of heat. When a given amount of heat is added to different substances, their temperatures increase by different amounts.
Heat capacity is an extensive property of matter, meaning it is proportional to the size of the system. Heat capacity C has the unit of energy per degree or energy per kelvin. When expressing the same phenomenon as an intensive property, the heat capacity is divided by the amount of substance, mass, or volume, thus the quantity is independent of the size or extent of the sample.
In general, when a material changes phase from solid to liquid, or from liquid to gas a certain amount of energy is involved in this change of phase. As an example, see the figure, which descibes phase transitions of water. Latent heat is the amount of heat added to or removed from a substance to produce a change in phase. When latent heat is added, no temperature change occurs.
The enthalpy of vaporization is a function of the pressure at which that transformation takes place. The liquid phase has a higher internal energy than the solid phase. This means energy must be supplied to a solid in order to melt it and energy is released from a liquid when it freezes, because the molecules in the liquid experience weaker intermolecular forces and so have a higher potential energy a kind of bond-dissociation energy for intermolecular forces.
The temperature at which the phase transition occurs is the melting point. Electrical resistivity and its converse, electrical conductivity , is a fundamental property of a material that quantifies how strongly it resists or conducts the flow of electric current. A low resistivity indicates a material that readily allows the flow of electric current. Note that, electrical resistivity is not the same as electrical resistance.
Electrical resistance is expressed in Ohms. While resistivity is a material property, resistance is the property of an object. Substances in which electricity can flow are called conductors. Conductors are made of high-conductivity materials such as metals, in particular copper and aluminium.
Insulators , on the other hand, are made of a wide variety of materials depending on factors such as the desired resistance. Semiconductors are materials, inorganic or organic, which have the ability to control their conduction depending on chemical structure, temperature, illumination, and presence of dopants. The name semiconductor comes from the fact that these materials have an electrical conductivity between that of a metal, like copper, gold, etc.
They have an energy gap less than 4eV about 1eV. In solid-state physics, this energy gap or band gap is an energy range between valence band and conduction band where electron states are forbidden. In contrast to conductors, electrons in a semiconductor must obtain energy e. To understand the difference between metals , semiconductors and electrical insulators , we have to define the following terms from solid-state physics:.
A possible crystal structure of Chlorine is orthorhombic structure. In metals, and in many other solids, the atoms are arranged in regular arrays called crystals. A crystal lattice is a repeating pattern of mathematical points that extends throughout space. The forces of chemical bonding causes this repetition. It is this repeated pattern which control properties like strength, ductility, density, conductivity property of conducting or transmitting heat, electricity, etc.
There are 14 general types of such patterns known as Bravais lattices. Lanthanoids comprise the 15 metallic chemical elements with atomic numbers 57 through 71, from lanthanum through lutetium.
These elements, along with the chemically similar elements scandium and yttrium, are often collectively known as the rare earth elements. Rhenium is a silvery-white, heavy, third-row transition metal in group 7 of the periodic table. The actinide or actinoid series encompasses the 15 metallic chemical elements with atomic numbers from 89 to , actinium through lawrencium.
Rutherfordium is a chemical element with atomic number which means there are protons and electrons in the atomic structure. The chemical symbol for Rutherfordium is Rf. Dubnium is a chemical element with atomic number which means there are protons and electrons in the atomic structure.
The chemical symbol for Dubnium is Db. Seaborgium is a chemical element with atomic number which means there are protons and electrons in the atomic structure.
The chemical symbol for Seaborgium is Sg. Bohrium is a chemical element with atomic number which means there are protons and electrons in the atomic structure.
The chemical symbol for Bohrium is Bh. Hassium is a chemical element with atomic number which means there are protons and electrons in the atomic structure. The chemical symbol for Hassium is Hs. Meitnerium is a chemical element with atomic number which means there are protons and electrons in the atomic structure. The chemical symbol for Meitnerium is Mt. Darmstadtium is a chemical element with atomic number which means there are protons and electrons in the atomic structure.
The chemical symbol for Darmstadtium is Ds. Roentgenium is a chemical element with atomic number which means there are protons and electrons in the atomic structure.
The chemical symbol for Roentgenium is Rg. Copernicium is a chemical element with atomic number which means there are protons and electrons in the atomic structure. The chemical symbol for Copernicium is Cn. Nihonium is a chemical element with atomic number which means there are protons and electrons in the atomic structure. The chemical symbol for Nihonium is Nh. Flerovium is a chemical element with atomic number which means there are protons and electrons in the atomic structure.
The chemical symbol for Flerovium is Fl. Moscovium is a chemical element with atomic number which means there are protons and electrons in the atomic structure. The chemical symbol for Moscovium is Mc.
Livermorium is a chemical element with atomic number which means there are protons and electrons in the atomic structure. The chemical symbol for Livermorium is Lv. Tennessine is a chemical element with atomic number which means there are protons and electrons in the atomic structure. The chemical symbol for Tennessine is Ts. Oganesson is a chemical element with atomic number which means there are protons and electrons in the atomic structure.
The chemical symbol for Oganesson is Og. Discoverer: Marinsky, Jacob A. Discoverer: Glenn T. Seaborg, Joseph W. Kennedy, Edward M. Abundance in Universe. Abundance in Sun. Abundance in Meteorites. Abundance in Earth's Crust. Abundance in Oceans. Abundance in Humans. Space Group Name. Space Group Number.
Crystal Structure. Electron Configuration. Valence Electrons. Oxidation State. Atomic Radius. Covalent Radius. Van der Waals Radius. Neutron Cross Section. Young Modulus. Shear Modulus. Bulk Modulus. Poisson Ratio. Mohs Hardness. Vickers Hardness.
Brinell Hardness. Apply market research to generate audience insights. Measure content performance. Develop and improve products. List of Partners vendors. Share Flipboard Email. Anne Marie Helmenstine, Ph. Chemistry Expert. Helmenstine holds a Ph. Tennessine is a synthetic element that was discovered in It is highly radioactive and….
History and Discovery Chlorine compound, sodium chloride table salt has been known by human civilizations since prehistoric times and evidence of use of rock salt have been found from as early as BC [1]. Physical Characteristics Chlorine is a non-metal. Chemical Characteristics Chlorine is a very reactive non-metal and has a reactivity that is intermediate between fluorine and bromine. PVC is used in making a wide range of products, including water pipes, car interiors, vinyl flooring, insulations of wire and blood bags.
Chlorine is widely used as a disinfectant as it can kill various kinds of bacteria. It is commonly used as a water disinfectant.
Chlorine is used in the manufacturing of paper and in textile industry. Chlorine is used in paints. Chlorine is used in making insecticides and pesticides. Chlorine is widely used in pharmaceutical industry for the manufacturing of large range of medicines, chloroform and disinfectants. However, due to the toxic effects of chlorine, its use has been greatly limited. Health Hazards Chlorine is highly toxic. Greenwood and Earnshaw, p. Greenwood and Earnshaw, pp.
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