physical science - Neutral Carbon Atom

Neutral Carbon Atom

Has an equal number of protons and electrons. It contains 6 protons in its nucleus, which defines its atomic number. The number of electrons in a it is also 6. Atomic mass of approximately 12.01 amu.

Excited State of Sodium

In quantum mechanics, an excited state of a system is any quantum state of the system that has a higher energy than the ground state

Quantum Numbers

A total of four are used to describe completely the movement and trajectories of each electron within an atom. 

The combination of all quantum numbers of all electrons in an atom is described by a wave function that complies with the Schrödinger equation.

Azimuthal Quantum Numbers

ℓ is a quantum number for an atomic orbital that determines its orbital angular momentum and describes aspects of the angular shape of the orbital. 

Is the second of a set of quantum numbers that describe the unique quantum state of an electron.

The others being the principal quantum number n, the magnetic quantum number m_ℓ, and the spin quantum number m_s.

Electronegativity

A chemical property that describes the power of an atom in a molecule to attract shared-pair electrons towards itself. 

There is a large difference in it for atoms from the left- and right-hand sides of the periodic table.

Fluorine has the highest electronegativity 

value = 4.0

Atomic Radius

Is a measure of the size of its atom, usually the mean or typical distance from the center of the nucleus to the outermost isolated electron. 

It decreases as you go across the periodic table.

Radon Electron Configuration

²²²Rn has a sufficiently long half-life (3.825 days) for it to be released from the soil and rock where it is generated. 

The instability of ²²²Rn, its most stable isotope, makes radon one of the rarest elements. 

Radon will be present on Earth for several billion more years despite its short half-life, because it is constantly being produced as a step in the decay chains of ²³⁸U and ²³²Th, both of which are abundant radioactive nuclides with half-lives of at least several billion years.

 [Xe]6s²4f¹⁴5d¹⁰6p⁶  

Third Electron Shell

Each shell can contain only a fixed number of electrons.

The first shell can hold up to two electrons, the second shell can hold up to eight electrons, the third shell can hold up to 18, continuing as the general formula of the nth shell being able to hold up to 2(n²) electrons.

Electron Affinity

The electron affinity is the potential energy change of the atom when an electron is added to a neutral gaseous atom to form a negative ion. 

So the more negative the electron affinity the more favorable the electron addition process is. 

Metalloids

Elements, that show an intermediate property both of metals and non-metals, present in periodic table. 

Elements of the periodic table behave both like metals and non-metals. 

The physical properties and chemical properties of metalloids are intermediate in nature.

Aufbau Principle

In Quantum chemistry, the Aufbau principle states that in the ground state of an atom or ion, electrons first fill subshells of the lowest available energy, then fill subshells of higher energy. 

The 1s subshell is filled before the 2s subshell is occupied. 

The electrons of an atom or ion form the most stable electron configuration possible.

Chromium Electron configuration

Half-filled and fully filled subshell have got extra stability. Therefore, one of the 4s² electrons jumps to the 3d⁵ so that it is half-filled. 

This give us the correct configuration of:

1s² 2s² 2p⁶ 3s² 3p⁶ 3d⁵ 4

Magnetic Quantum Number

A quantum number used to distinguish quantum states of an electron or other particle according to its angular momentum along a given axis in space. 

The orbital magnetic quantum number (m_l or m) distinguishes the orbitals available within a given subshell of an atom. 

It specifies the component of the orbital angular momentum that lies along a given axis, conventionally called the z-axis, so it describes the orientation of the orbital in space. 

Noble Gases

Under standard conditions, the first six of these elements are odorless, colorless, monatomic gases with very low chemical reactivity and cryogenic boiling points. 

The intermolecular force between noble gas atoms is the very weak London dispersion force, so their boiling points are all cryogenic, below 165 K (−108 °C; −163 °F).

Metallic properties

Elements with metallic character occur in certain groups or columns of elements, including the alkali metals, alkaline earth metals, transition metals (including the lanthanide and actinides below the main body of the periodic table), and the basic metals.  

As you go down a group of elements the metallic properties increase in strength.

Rubidium Electron Configuration

The second most electropositive of the stable alkali metals and has a very low first ionization energy of only 403 kJ/mol.  

It has an electron configuration of [Kr]5s¹ and is photosensitive.

Element

Defined a as pure substance composed of atoms that all have the same number of protons in the atomic nucleus.

Orbital Shape

Each orbital in an atom is characterized by a set of values of three quantum numbers n, ℓ, and m_ℓ that correspond to electron's energy. 

Its orbital angular momentum is projected along a chosen axis, magnetic quantum number. 

Real-valued orbitals can be formed as linear combinations of m_ℓ and −m_ℓ orbitals.

Energy Levels

A quantum mechanical system or particle that is confined spatially can only take on certain discrete values of energy, called energy levels. 

The energy levels of the electrons bound by the electric field of the nucleus. 

A quantum mechanical system or particle that is confined spatially can only take on certain discrete values of energy, called energy levels. 

The energy levels of the electrons bound by the electric field of the nucleus. 

d suborbitals

An orbital can be occupied by a maximum of two electrons, each with its own projection of spin, m_s.

The simple names s orbital, p orbital, d orbital, and f orbital refer to orbitals with angular momentum quantum number ℓ = 0, 1, 2, and 3. 
They are derived of certain series of alkali metal spectroscopic lines as sharp, principal, diffuse, and fundamental.  Max. = 10 e^-

Halogens

Halogens are a group of elements in Group 17 of the periodic table.

They are known for their high reactivity, particularly with alkali and alkaline earth metals.

Halogens readily form salts when they react with metals, such as sodium chloride (NaCl).

Atomic Number

For ordinary nuclei composed of protons and neutrons, this is equal to the proton number or the number of protons found in the nucleus of every atom of that element. 

The atomic number can be used to uniquely identify ordinary chemical elements.

Iron (II) Ion

Refers to the oxidation state of iron 

where it has lost two electrons.

Ferrous iron, denoted as Fe²⁺.

Examples: iron(II) sulfate (FeSO₄) 

and iron(II) chloride (FeCl₂).

Electron Configuration 

1s²2s²2p⁶3s²3p⁶3d⁶

Noble Gas Configuration

[Ar]3d⁶

Exceptional Electron Configurations

Refer to deviations from the expected electron arrangement in atoms, particularly in transition metals and heavier elements.

The stability of these configurations often arise due to increased stability associated with half-filled or fully filled subshells.

Hund’s Rule

In chemistry and atomic physics, Hund’s rule states that electrons fill a suborbital as singles before they start forming doubles and that all of the singles in the suborbital have the same spin. 

The rule gets it name for German physicist Friedrich Hund, who formulated it around 1927.

F Sublevel Orbitals

 f orbitals are found in the higher energy levels, specifically in the fourth and higher principal energy levels n=4 and above.

Azimuthal quantum number (l) for f orbitals is 3.

Seven f orbitals in each f sublevel, designated as f_xx, f_xy, f_xz, f_yz, f_yx, f_zx, and f_zz.

Cesium Element

Belongs to the alkali metals Group 1.

Physical Property is a soft, gold-colored metal that is highly reactive, especially with water.

Used in atomic clocks, which are highly accurate timekeeping devices.

Most stable isotope of cesium is cesium-133, which is used as a standard for defining the second.

Copper (I) Ion

Also known as cuprous ion, has a +1 oxidation state Cu¹⁺.

Forms when copper loses one electron.

Copper (I) is less stable than Copper (II) due to its tendency to oxidize.

Compounds include cuprous oxide Cu₂O and cuprous chloride CuCl.

Noble Gas Configuration [Ar]3d¹⁰

Krypton Noble Gas

Chemically inert does not readily react with other elements or compounds.

Complete valence shell with eight electrons, contributing to its stability.

Electron Configuration

1s²2s²2p⁶3s²3p⁶3d¹⁰4s²4p⁶  

Highest Energy Orbital

The Aufbau principle states that electrons fill orbitals starting from the lowest energy level to the highest.

The 5s orbital is filled after the 4p orbitals.

Ultimately, the 7s orbital has the highest energy among the orbitals filled in the Aufbau sequence.

Ionization Energy

Factors Affecting Ionization Energy: Atomic size, nuclear charge, and electron shielding influence the first ionization energy.

Reactivity: Elements with low first ionization energies tend to be more reactive, especially metals.

Partially Filled D-Orbitals

Partially filled d-orbitals contain one or more electrons but are not completely filled with the maximum of ten electrons.

d-orbitals are found in the third energy level and higher, specifically in transition metals.

The presence of unpaired electrons in d-orbitals contributes to the chemical properties of transition metals.

Ionic Bonds

Occurs between metals and nonmetals.

Metals lose electrons to become positively charged cations.

Nonmetals gain electrons to become negatively charged anions.

Ionic compound is usually crystalline in structure.

High melting and boiling points due to strong attractions.

Noble Gas Electron configuration

Chemically inert due to their stable electron configurations, making them less likely to react with other elements.

Notation are often abbreviated using the nearest noble gas to simplify the representation of an element's electron arrangement.

Oxidation State

The oxidation state of an atom is equal to the total number of electrons which have been removed from an element producing a positive oxidation state, or added to an element producing a negative oxidation state to reach its present state.

Lanthanide Series

Series of chemical elements comprises at least the 14 metallic chemical elements with atomic numbers 57–70, from lanthanum through ytterbium. 

In the periodic table, they fill the 4f orbitals. 

Lutetium (element 71) is also sometimes considered a lanthanide, despite being a d-block element and a transition metal.

Alkali Metals

Highly Reactive: with water, forming hydroxides and releasing hydrogen gas.

Low Density: lithium, sodium, and potassium being less dense than water.

Electropositivity: They have a strong tendency to lose their outermost electron, resulting in a +1 oxidation state.

Liquid Phase

Solvent: A substance that dissolves a solute, forming a solution in the liquid phase.

Reaction Kinetics: The study of the rates of chemical reactions occurring in the liquid phase.

Mercury Hg is an element that exists as a liquid at room temperature.

Anions

An anion is a negatively charged ion that is formed when an atom or molecule gains one or more electrons. Anions are essential in understanding both atomic structure and organic reaction mechanisms.

Transition Metals

Coordination Compounds: Complexes formed when transition metals bond with ligands, which are molecules or ions that donate electron pairs.

Ligands: Atoms, ions, or molecules that can donate electron pairs to a central metal atom in a coordination complex.

Oxidation States: The charge of a transition metal in a compound, which can vary widely due to the ability to lose different numbers of electrons.

Chemical Properties

A characteristic that can only be observed during a chemical reaction.

Reactivity: The ability of a substance to undergo a chemical change with another substance.

Electronegativity: A measure of an atom's ability to attract and hold onto electrons in a chemical bond.

Isotopes

Variants of chemical elements that possess the same number of protons and electrons, but a different number of neutrons.

Variation of an element that possesses the same atomic number but a different mass number. 

Differ in the number of neutrons held by their respective nuclei.