Elements of period 1

Elements of period 1

A period 1 element is one of the chemical elements in the first of seven rows (or periods) of the periodic table of chemical elements. The period number indicates the number of the main energy level that the electrons begin to fill. The first period only fills the first energy level (1s) and contains fewer elements than any other row in the table, just two: hydrogen and the helium. These elements are grouped in the first row by virtue of properties that they share with each other.

Hydrogen (Z=1) has properties very similar to those of the halogens, but because its chemical properties bring it closer to the alkali metals, hydrogen is often represented together with them.

Helium (Z=2) behaves like a noble gas and is found at the end of the row, placed in group 18 (VIIIA). The next period contains eight elements, since it is not until then that it occurs another element that behaves like a noble gas (that is, that has the same properties). This situation can be explained by current theories of atomic structure.

Overview

The periodic table is arranged in rows to illustrate recurring (periodic) trends in the chemical behavior of the elements as the atomic number increases: a new row is started when the chemical behavior repeats itself again, meaning that elements with similar behavior are found in the same vertical columns. These horizontal rows of the periodic table are called periods. An element in one period differs from the previous one by having one more unit of its atomic number. It happens in the case of the groups of the periodic table, the elements that make up the same row have different properties, but similar masses: all the elements of a period have the same number of orbitals. Following that rule, each element is placed according to its electronic configuration. This first period is very short, containing fewer elements than any other row in the table, only hydrogen and helium; both have only the 1s orbital, so that match as elements of block s.

Electronic configuration

A period 1 element is one of the chemical elements in the first row (or period) of the periodic table of chemical elements. In the quantum mechanical description of atomic structure, this period corresponds only to the filling of the 1s orbital, which is the lowest energy electron orbital.

Configuration (also called electron configuration) is the way in which electrons are arranged in an atom, molecule, or other physical structure, according to the orbital approximation in which the wave function of the system is expressed as a product of antisymmetrized orbitals. Period 1 elements do not follow the octet rule; that is to say, that the atoms of the elements of this period do not complete their last energy levels with a quantity of eight electrons, according to Hund's Rule. The maximum number of electrons that the two elements can accommodate in period 1 is two; an element with a two-electron configuration is called a "duo".^{[citation needed]}

Elements

Hydrogen

The main engine of a space shuttle takes off using hydrogen and oxygen as fuels for your trip.

Hydrogen (H) is the chemical element with atomic number 1. Under normal conditions of pressure and temperature, hydrogen is a colorless, odorless, non-metallic, tasteless, and highly flammable diatomic gas, with the molecular formula H2. With an atomic mass of 1.00797 amu, hydrogen is the lightest element.

Hydrogen is the most abundant chemical element, accounting for approximately 75% of the elemental mass in the universe. Main sequence stars are composed primarily of hydrogen in the plasmatic state. Elemental hydrogen is relatively rare on Earth, and is produced industrially from hydrocarbons such as methane, after which elemental hydrogen is used "captively" (ie at the place of production). The largest markets are split almost evenly between upgrading fossil fuels, such as hydrocracking, or ammonia production, mainly by the fertilizer market. Hydrogen can be produced from water through a process known as electrolysis (which consists in the separation of the elements that form a compound by applying electricity: the decomposition into ions occurs first, followed by various effects or secondary reactions according to the specific cases), but this process has a commercial cost considerably higher than the production of hydrogen from natural gas.

The most common naturally occurring isotope of hydrogen, known as the hydrogen atom, has a single proton and no neutrons. In ionic compounds, it can either assume a positive charge, becoming a cation composed of a single proton, or a negative charge, becoming an anion known as a hydride. Hydrogen can form compounds with most elements and is present in water and most organic compounds. It has an especially important role in the acid-base reaction, in which many reactions involve the exchange of protons between soluble molecules. Being the only neutral atom for which the Schrödinger equation can be solved analytically, the study of the energetics and spectrum of the hydrogen atom has played a key role in the development of quantum mechanics.

The interactions of hydrogen with various metals are very important in metallurgy, as many metals can undergo hydrogen embrittlement, and in the development of safe methods for storing it as a fuel. Hydrogen is highly soluble in many compounds including rare earth metals and transition metals and can dissolve in both crystalline and amorphous metals. The solubility of hydrogen in metals is influenced by local distortions or impurities in the metal's crystal lattice.

Helium

Capture a gas container filled with helium.

Helium (He) is a monatomic, inert, colorless, odorless, tasteless and non-toxic chemical element that heads the group of noble gases in the periodic table, and has atomic number 2. Its boiling points and fusion are the lowest of all the elements, and exist only in the form of a gas, except under extreme conditions.

Helium was discovered in 1868 by French astronomer Pierre Janssen, who first detected the substance as an unknown yellow spectral line signature in the light of a solar eclipse. In 1903, large reserves of helium were discovered in natural gas fields in the United States, the world's leading provider of this gas. This substance is used in cryogenics, in underwater respiration systems, to cool superconducting magnets, in helium dating, to inflate balloons, to provide lift for airships and as a shielding gas in industrial applications such as arc welding and silicon wafer production. Inhalation of a small volume of this gas temporarily changes the timbre and quality of the human voice. The behavior of the two fluid phases of liquid helium-4, helium I and helium II, is important for researchers studying quantum mechanics, and more specifically the phenomenon of superfl uidity, as well as for researchers studying the effects of temperatures near absolute zero on matter, such as superconductivity.

Helium is the second lightest element and also the second most abundant in the observable universe. Most helium was formed during the Big Bang, but helium continues to be created as a result of nuclear fusion of hydrogen in stars On Earth, helium is relatively rare and is created by the natural decay of some radioactive elements, as the alpha particles they emit are helium nuclei. This radiogenic helium is trapped with natural gas at concentrations up to 7% by volume, where it is extracted commercially through a low-temperature separation process called fractional distillation.