Moseley established the Modern Periodic Law, which states that “physical and chemical properties of elements are periodic functions of their atomic numbers.” Elements are arranged in the modern periodic table according to their atomic numbers, which, as previously stated, are directly related to their physical and chemical properties. That is why elements in the periodic table exhibit periodicity in their physical and chemical properties. Atomic size, for example, decreases as we move through a period from left to right. The graph below depicts the variation of periodic properties of elements. Despite the fact that there are some exceptions that do not follow these periodic table trends. Periodicity is caused by the recurrence of similar electronic configurations in the periodic table. As a result, elements with similar electronic configurations have similar properties. Periodic trends provide chemists with a quick and easy tool for predicting element properties.
As previously stated, a metal atom’s characteristic chemical property is to lose one or more of its electrons to form a positive ion. Certain metals, however, lose electrons much more quickly than others. Cesium (Cs) in particular can give up its valence electron more easily than lithium (Li). In fact, the ease with which the alkali metals (the elements in Group 1) give up an electron varies as follows: Cs > Rb > K > Na > Li
Every object in our environment can be divided into two types of elements: metals and nonmetals. Non-metals include your books, clothes, pencil, water bottle, bag, table, and door. Hence, it is dangerous to understand the properties of metals and nonmetals and how to distinguish between them. The periodic table is an arrangement of elements based on the chemical properties that they possess. The metals are on the left side of the periodic table, and the nonmetals are on the right. The rows of the table are referred to as periods, and the columns are referred to as groups. There are 92 elements known to exist in nature, 70 of which are metals and 22 of which are non-metals. That being said, when we talk about chemical property, we are referring to a property of a substance that can be observed or measured when it undergoes a chemical change. Only by performing a chemical reaction can a chemical property be observed. The molecular structure of a substance changes when it undergoes a chemical change. The physical property of a substance is anything that can be measured without changing the identity or chemical composition of the substance. A physical change involves the formation of a new arrangement of matter, but the atoms and molecules retain their original structure.
The chemical properties of a substance can be observed or measured when it undergoes a chemical change. Physical properties are those that can be observed without causing a chemical reaction. To demonstrate the property, a chemical reaction must be carried out. There is no need for a chemical reaction in this case. Chemical properties are linked to a substance’s chemical bonds. Such a relationship does not exist between physical properties. It can be used to predict how different substances will react. It is primarily used to identify or describe a substance.
Metals and nonmetals are two types of materials that we encounter on a daily basis. Elements are classified as metals or nonmetals, and it is critical to understand whether an element is a metal or a nonmetal. Metals (such as copper and aluminium) conduct heat and electricity well, whereas nonmetals (such as phosphorus and sulphur) are insulators. Materials are classified as described above based on their properties.
Physical and chemical properties of metals and nonmetals
The majority of the elements in the periodic table depicted above are metals. Metals are classified into several types:
- Metals from the alkaline earth
- Metals containing alkali
- Metals in transition
- Actinides, as well as
Metals on the left side of the periodic table are separated from non-metals by a zigzag line that runs from Carbon (C) to Phosphorus (P), Selenium (Se), Iodine (I), and Radon (R) (Rn). As a result, these chemical elements and everything to their right are known as non-metals, while the row to their left is known as semi-metals or metalloids. They have properties in common with both metals and nonmetals.
- Metals exist in solid form. With the exception of mercury, which is a liquid in its natural state, all metals are solid.
- Metals are naturally malleable. They are able to be beaten into thin sheets. Elements such as aluminium, gold, and silver, for example, can be beaten into thin sheets for common use.
- Metals are malleable. Metals can thus be stretched into thin wires. We can produce copper and aluminium wires. In the same way, all metals are ductile.
- Metals are excellent heat and electricity conductors. Heat and electricity can both pass through metals because of this property. Every metal is an excellent heat and electricity conductor.
- Metals reflect light. Metals are lustrous because of this property, and they reflect light incident on their surface. Metals can also be polished, which is one of the reasons why they are used to make jewellery and are desired by both men and women.
- Metals are extremely strong and hard, with the exception of sodium and potassium. They can be slashed with a knife.
- Metals can also produce sound. When they are rung or hit with any object, they make a sound.
- Metals have both a high melting and boiling point.
- Metals have a very high density.
- Metal objects are always opaque and never transparent or translucent.
- Metals corrode very quickly and easily.
- Metals easily lose electrons. Their outer shell contains one, two, or three electrons.
- When most metals come into contact with oxygen, they produce metal oxides.
- Metals are electropositive elements with low electro-negativities.
- Metals are also excellent reducing agents.
Non-metal elements are those that lack the properties of metals. In comparison to metals, the number of non-metals on the periodic table is very small. Nonmetals are found on the periodic table’s right side. Non-metals include hydrogen, carbon, nitrogen, phosphorus, oxygen, sulphur, selenium, all halogens, and noble gases.
- When beaten, nonmetals become brittle and break into pieces. Sulphur and phosphorus are two examples.
- Because nonmetals are not ductile, they cannot be formed into thin wires. Because they do not lose electrons while transmitting energy, nonmetals are insulators or poor conductors of electricity and heat.
- They can exist as solids, liquids, or gases at room temperature.
- They aren’t sonorous at all.
- They are capable of being transparent.
- Non-metals typically have 4 to 8 electrons in their outer shell.
- Nonmetals have a proclivity to gain or accept valence electrons. Nonmetals react with oxygen to form acidic oxides when exposed to them.
- Nonmetals are electro-negative elements with a high electro-negativity. Nonmetal elements are excellent oxidising agents.
- Water has no effect on these elements.
Chemical properties of matter
Chemical properties are any properties of matter that can only be observed and measured by undergoing a chemical change or reaction. Chemical properties cannot be determined by touching or viewing a sample; the sample’s structure must be altered for the chemical properties to be visible.
- Interactions with other chemical
- Number of coordination
- Formation enthalpy
- Combustion heat
- Oxidation conditions
- Chemical endurance
Physical properties of alkanes
Paraffin is another name for an alkane. It is made up of carbon and hydrogen atoms that are joined together in a tree-like structure by a single covalent bond. Alkanes have the general formula CH2n+2. The structure of methane (CH4), one of the most common alkanes, is shown below.
The following are some important physical properties of alkanes:
- Alkanes have no colour and no odour.
- They have weak Van der Waals attraction forces.
- At 298K, alkanes with 1-4 carbon atoms are gases, alkanes with 5-17 carbon atoms are liquids, and alkanes with 18 or more carbon atoms are solids.
- It grows in proportion to the increasing molecular weight, just as the Van Der Waals force grows in proportion to the increasing molecular weight. The boiling point of straight-chain alkanes is higher than that of their structural isomers.
- It also rises with increasing molecular weight because higher alkanes are generally solids, making it difficult to break the intermolecular forces of attraction between them. Even-numbered alkanes have better packing in the solid phase than odd-numbered alkanes because they form a well-organized structure that is difficult to break, so they have a higher melting point than odd-numbered alkanes
Q. Why are alkanes referred to as paraffin?
Ans: The term “paraffin” comes from the Latin language. Because of their low affinity for a general reagent, it is formed by the words parum, which means little, and affinities, which means reactivity. We can say that alkanes are inert and only react under extreme conditions. This is due to the fact that alkanes form only single bonds between carbon and hydrogen atoms, which are relatively strong and difficult to break, and also because carbon and hydrogen have similar electronegativities, resulting in nonpolar molecules. As a result, they undergo limited reactions, are subjected to specific conditions, and are referred to as paraffin.
Q. Which of the following metals is a poor heat and electricity conductor?
Ans: Lead is a poor heat and electricity conductor.