General Chemistry

Chemical Formula – The chemical formula for a substance shows its chemical composition. – This represents the elements present as well as the ratio in which the atoms of the elements occur. – The formula for a single atom is the same as the symbol for the element. Thus, Na …

Democritus’s ideas about atoms – The Greek philosopher Democritus (470–400 BC) suggested that all matter is composed of tiny, discrete, indivisible particles that he called atoms. – His ideas, based entirely on philosophical speculation rather than experimental evidence, were rejected for 2000 years. – By the late 1700s, scientists began …

Difference Between Heat and Temperature – Heat is one form of energy. – Many forms of energy can be interconverted and that in chemical processes, chemical energy is converted to heat energy or vice versa. – The amount of heat a process uses (endothermic) or gives off (exothermic) can tell …

– In this topic, we will discuss The Density and Specific gravity: Definition and Solved problems. Definition of Density – In science, we use many terms that involve combinations of different units. – Such quantities may be thought of as unit factors that can be used to convert among these …

– In this topic, we will discuss The Physical and Chemical properties of Matter and The Physical and Chemical Changes. Physical and Chemical  properties – To distinguish among samples of different kinds of matter, we determine and compare their properties. – We recognize different kinds of matter by their properties, …

What’s the difference between Solids, liquids, and gases? – It is easy to tell the difference between solids, liquids and gases – A solid has a fixed shape and a fixed volume. It does not flow. Think of all the solid things around you: their shapes and volumes do not …

Definition of Matter and Energy What is Matter? – Matter is anything that has mass and occupies space. – Mass is a measure of the quantity of matter  in a sample of any material. – The more massive an object is, the more force is required to put it in …

Molecular Orbitals for Heteronuclear Diatomic Molecules – In the previous subject, we talk about but electronic structures and bonding properties of some of The homonuclear diatomic molecules. but in this subject, we will talk about Molecular Orbitals for Heteronuclear Diatomic Molecules (MO Theory) – When two different atoms are bonded …

Molecular Orbitals for Homonuclear Diatomic Molecules – In the previous subject, we talk about but electronic structures and bonding properties of some of The Heteronuclear Diatomic Molecules. but in this subject, we will talk about Molecular Orbitals for Homonuclear Diatomic Molecules (MO Theory) – After having discussed the basic principles …

MCQ on Chemical Bonding – Orbital Theory – In this subject, you will find 46 questions and answers MCQ on Chemical Bonding – Orbital Theory 1. When a chemical bond between two atoms is formed, the potential energy of the system_______ (a) decreases (b) increases (c) remains the same (d) …

Molecular Orbital Theory – The molecular orbital theory proposed by Hund and Mulliken in 1932 explains the formation of a covalent bond in a better way.  – According to molecular orbital theory all atomic orbitals of the atoms participating in molecule formation get disturbed when the concerned nuclei approach nearer. …

MCQ on the structure of the atom – In this subject, you will find 50 questions and answers MCQ on Chapter structure of atom – wave mechanical approach 1. The number of unpaired electrons in oxygen atom is_______ (a) 1 (b) 2 (c) 3 (d) 4 Answer. (b) 2. The …

– In this subject, we will discuss the difference Between Electronegativity and Electron Affinity Electron Affinity  – A neutral atom can accept an electron to form a negative ion. In this process, in general, energy is released. – The electron affinity (EA) of an element is the amount of energy released …

– The ionization energy (IE) of an element is defined as the energy needed to remove a single electron from an atom of the element in the gaseous state. Ionization Energy – The process of removing an electron from an isolated atom to form a positive ion is called ionization. …

– In this subject, we will discuss the rules of Electron Configuration Of Elements  Electron Configuration Of Elements – We have seen before that to define completely the state of an atom it is obligatory to refer to all the four quantum numbers (n, l, m, and s) of every …

– In this subject, we will discuss the Distribution of Electrons in Orbitals according to Hund’s Rule. Energy Distribution and Orbitals – In our earlier discussion, we have seen that the energy of an electron is determined by the first two quantum numbers (n) and (l), while the other two …

– The Pauli exclusion principle is of immense value in telling the maximum number of electrons accommodated in any shell. Quantum Numbers and the Energy of an Orbital – The nature of an electron, its position, and energy, is fully implied only by mentioning the values of four quantum numbers ascribed …

Quantum Numbers – Bohr’s electronic energy shells or levels, designated as Principal Quantum Numbers (n), could hardly explain the hydrogen spectrum adequately. – Spectra of other elements that are quite complex, also remained unexplained by this concept. – Many single lines of the spectra are found to consist of a …

Schrödinger Wave Equation – In order to provide sense and meaning to the probability approach, Schrödinger derived an equation known after his name as the Schrödinger Wave Equation.  – Calculation of the probability of finding the electron at various points in an atom was the main problem before Schrödinger.  – …

– Heisenberg’s uncertainty Principle: As it is impossible to know the position and the velocity of any one electron on account of its small size, the best we can do is to speak of the probability or relative chance of finding an electron with a probable velocity. Heisenberg’s Uncertainty Principle …