Molecular formulae and structural formulae of organic compounds

Chemists use a variety of ways to represent organic compounds. It is useful to know all of these so that you can recognize a molecule regardless of how it is represented. In this post, we will discuss the Molecular formulae and structural formulae of organic compounds. Structural formulae A structural formula is a graphic representation […]

How does carbon bond with other atoms?

Carbon has a number of unique properties that influence how it behaves and how it bonds with other atoms: 1 ) Carbon has four valence electrons. Carbon can thus form a maximum of four bonds with other atoms as depicted in Figure 1. 2 ) Carbon can bond strongly with other carbon atoms forming single […]

Activation energy & chemical Reaction – chemistry Study notes

Activation energy is the minimum energy required to start a chemical reaction. The colliding particles must possess at least this amount of energy for a reaction to take place. Most of the reactions are exothermic but only a few are totally spontaneous and begin without help at normal temperatures (e.g. sodium or potassium reacting with […]

What is Covalent Bonding? – study notes

Covalent bonds are formed when atoms, rather than gaining or losing electrons, share them. Covalent bonds differ from ionic bonds in that there is no transfer of electrons involved. Electrical attraction between the nuclei of adjacent atoms and the shared electrons causes the atoms in a molecule to be held together. This force of attraction […]

Important formulas related to Atomic Structure

In this post, you will find a bunch of important formulas related to atomic structure. formulas related to atomic number & mass number (a) Atomic number (Z) = number of electrons = number of protons (b) Mass number (A) = number of protons + number of neutrons = atomic number + number of neutrons (c) […]

Electron shells for the first 20 elements & shells filling rules

In this post, we will present a diagram displaying the electron shells for the first 20 elements of the Periodic Table.The number of electrons increases by 1 each time. (It is the same as the proton number.) The shells fill according to the rules given in the next section. Electron shells filling rules Electrons are […]

The atoms of the first 20 elements in the periodic table

In the Periodic Table, the elements are arranged in order of increasing proton number. Here is a quick list of the names of the first 20 elements in the periodic table: hydrogen, helium, lithium, beryllium, boron, carbon, nitrogen, oxygen, fluorine, neon, sodium, magnesium, aluminium, silicon, phosphorus, sulphur, chlorine, argon, potassium, & calcium. In this post, […]

Isotopes – revision notes

Isotopes are atoms of the same element, with different numbers of neutrons.Most elements have isotopes. For example, calcium has six, magnesium has three, iron has four, and chlorine has two. Carbon Isotopes All carbon atoms have 6 protons. But not all carbon atoms are identical. Some have more neutrons than others. Most carbon atoms are […]

Acid, Alkali, and pH scale – chemistry notes

Here you will get the fundamental concepts of acids, alkalies, and pH value (concepts, measurements, & examples). What is an Acid? An acid is a substance that produces hydrogen ions, H+, in an aqueous solution. For example, solutions of:● hydrochloric acid (HCl) contains hydrogen (H+) ions and chloride (Cl–) ions● sulfuric acid (H2SO4) contains hydrogen […]

Sources of metals & methods of their extraction

In this post, we will discuss the ways of extraction of metals. In this process, we will cover ores, sources of metals, & different methods of extraction of metals (including iron extraction). Where do metals come from? A few metals, such as gold, silver and platinum, occur naturally on Earth as elements. These are metals […]

Molar form of Enthalpy equation – how to derive?

The Enthalpy equation is represented as ΔH = ΔU + pΔV …(1) where ΔU is the change in internal energy and ΔV is the change in volume of the system. The difference between ΔH and ΔU is not usually significant for solids and liquids. However, when the systems involve gases, the difference becomes significant. Here, […]

Enthalpy – chemistry revision notes for class 11

Enthalpy of a system may be defined as the sum of the internal energy(U) and the product of its pressure(p) and volume(v). It is denoted by the symbol H and is given by: H = U + pV Getting the Heat Transfer equation (derivation) Change in the internal energy of a system is:ΔU= q + […]

Carbon & its bonding, allotropes, Physical Nature & Compounds

Carbon is non-metal. In nature, it occurs in its pure form as diamond and graphite. When fuels burn, the carbon in them reacts with oxygen to form carbon dioxide. Carbon compounds hold the key to plant and animal life on the earth. Carbon circulates through air, plants, animals, and soil by means of complex reactions. […]

Thermodynamics – class 11 chemistry notes

This post covers Thermodynamics with class 11 chemistry notes. The branch of science which deals with the study of different forms of energy and their interconversion is called thermodynamics. Thermodynamics means the flow of heat. Thermodynamics is one of the fundamental subject in physical chemistry It’s a science of macroscopic properties i.e. properties of matter […]

Thermodynamics Processes – FAQ

In this post, we will cover a few important & frequently asked questions on Thermodynamics Processes. The state of a thermodynamic system can be changed by a process. In other words, a process gives the path or operation by which a system changes from one state to another. The process may be accompanied by an […]

Isotherm, Isobar & Isochore graphs

When we study gas laws (Boyle’s law, Charles’ law & Pressure Law), we come across terms like Isotherm, Isobar, and Isochore. Here, in this post, we will discuss these. What is Isotherm? If we draw Boyle’s law graphs at diff temperatures then we get curves shown in figure 1. Boyle’s law is expressed as V […]

Atoms – FAQ with answers

All atoms are made of three basic particles: the proton, electron, and neutron. Let’s see how these were identified or discovered. How were electrons identified? The first strong evidence that something existed smaller than an atom came in 1897. English physicist J. J. Thomson discovered thatelectricity passing through a gas caused the gas to give […]

Molar Mass – concepts and formula

The mass of one mole of a substance in grams is called its molar mass. The molar mass in grams is numerically equal to atomic/molecular/formula mass in u. The molar mass of water = 18.02 g mol-1The molar mass of sodium chloride = 58.5 g mol-1 Molar mass is the mass of a single mole. […]

Combined Gas Law or gas equation | the Ideal Gas Equation

We will derive the following here (1) combined gas law or gas equation & (2) the Ideal Gas equation. For these, we will use Boyle’s law, Charles’ law, Pressure law, and Avogadro’s law for gases. The Combined Gas Law or Gas Equation Boyle’s and Charles’ laws give separately variations of the volume of a gas […]

Avogadro’s Law (Volume–Amount Relationship)

Avogadro’s Law offers Volume-Amount Relationship of gases. Amadeo Avogadro in 1811, put forward a relationship between volume of a gas to the number of molecules at constant temperature and pressure. This has now been accepted as a law and is known as Avogadro law. Avogadro’s law states that equal volumes of all gases under the […]

The gaseous state of matter – Facts and FAQs

The gaseous state is the simplest state of matter. In this post, we will cover some important facts and frequently asked questions on gases and the gaseous state of matter. Number of gas elements in the periodic table A look at the periodic table shows that only eleven elements are gases under normal conditions as […]

Solving Numerical problems using Boyle’s law

Here we will present a set of solved numerical problems that use Boyle’s law formula to solve the numerical problems on gas. The primary formula that will be used to solve these numerical problems is p1V1 = p2V2 = constant. where p1 and V1 are initial pressure and initial volume of the gas respectively. Similarly, […]

How Bonding type decides Boiling and melting points

In this post, we will see how the type of bonding influences the melting point and the boiling point of a substance. Simple covalent molecules such as H2, F2, O2, CH4, etc. are gases at room temperature. They form molecular crystals which have low melting and boiling points. The intermolecular interactions between these covalent molecules […]

Intermolecular Forces versus Thermal Energy of three states of matter

In this post, we will first define Thermal energy, and then we will see how competition between molecular interaction energy (Intermolecular Force based energy that keeps molecules together) and thermal energy (that moves the molecules apart) influences the states of matter. What is Thermal Energy? Thermal energy is the energy of a body due to […]

Intermolecular Forces – Types & features

The forces of attraction and repulsion between interacting particles (atoms or molecules) are called intermolecular forces. Such forces exist in all states of matter and are responsible for many structural features and physical properties of matter. The intermolecular forces are weak forces. In this post, we will discuss different types of intermolecular forces with their […]

States of matter – chemistry revision notes

This post briefly discusses the states of matter with their important characteristics. We also define the Triple point with one example. Three States Of Matter – with characteristics Matter exists in three different physical states, namely solid, liquid and gaseous states. The important characteristics of the three states are: Solid state: A solid possesses a […]

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