ELEMENT: Chemical element, also called element, any substance that cannot be decomposed into simpler substances by ordinary chemical processes. Elements are the fundamental materials of which all matter is composed. This article considers the origin of the elements and their abundances throughout the universe. The geochemical distribution of these elementary substances in the Earth’s crust and interior is treated in some detail, as is their occurrence in the hydrosphere and atmosphere. The article also discusses the periodic law and the tabular arrangement of the elements based on it.
Proton
Protons, together with electrically neutral particles called neutrons, make up all atomic nuclei except for the hydrogen nucleus (which consists of a single proton). Every nucleus of a given chemical element has the same number of protons. This number defines the atomic number of an element and determines the position of the element in the periodic table. When the number of protons in a nucleus equals the number of electrons orbiting the nucleus, the atom is electrically neutral.
Neutron
neutral subatomic particle that is a constituent of every atomic nucleus except ordinary hydrogen. It has no electric charge and a rest mass equal to 1.67493 × 10−27 kg—marginally greater than that of the proton but nearly 1,839 times greater than that of the electron. Neutrons and protons, commonly called nucleons, are bound together in the dense inner core of an atom, the nucleus, where they account for 99.9 percent of the atom’s mass. Developments in high-energy particle physics in the 20th century revealed that neither the neutron nor the proton is a true elementary particle; rather, they are composites of extremely small elementary particles called quarks. The nucleus is bound together by the residual effect of the strong force, a fundamental interaction that governs the behaviour of the quarks that make up the individual protons and neutrons.
Shells
An electron shell is the outside part of an atom around the atomic nucleus. It is a group of atomic orbitals with the same value of the principal quantum number n. Electron shells have one or more electron subshells, or sublevels.
Electron
Valence electron
Valence electron, any of the fundamental negatively charged particles in the outermost region of atoms that enters into the formation of chemical bonds. Whatever the type of chemical bond (ionic, covalent, metallic) between atoms, changes in the atomic structure are restricted to the outermost, or valence, electrons. They are more weakly attracted to the positive atomic nucleus than are the inner electrons and thus can be shared or transferred in the process of bonding with adjacent atoms. Valence electrons are also involved in the conduction of electric current in metals and semiconductors.
lightest stable subatomic particle known. It carries a negative charge of 1.602176634 × 10−19 coulomb, which is considered the basic unit of electric charge. The rest mass of the electron is 9.1093837015 × 10−31 kg, which is only 1/1,836the mass of a proton. An electron is therefore considered nearly massless in comparison with a proton or a neutron, and the electron mass is not included in calculating the mass number of an atom.
Standard notation
Just the normal way of writing the equation
Bohr Diagram
Niels Bohr proposed an early model of the atom as a central nucleus containing protons and neutrons being orbited by electrons in shells. As previously discussed, there is a connection between the number of protons in an element, the atomic number that distinguishes one element from another, and the number of electrons it has. In all electrically-neutral atoms, the number of electrons is the same as the number of protons. Each element, when electrically neutral, has a number of electrons equal to its atomic number.
Nomenclature
the devising or choosing of names for things, especially in a science or other discipline.
Skeleton Equation
A skeleton equation is when your chemical reaction is written with the chemical formulas that represent each substance that takes part in the reaction. Examples: The word equation: Sodium + Chlorine → Sodium Chloride.
Balanced equation
A balanced equation is an equation for a chemical reaction in which the number of atoms for each element in the reaction and the total charge is the same for both the reactants and the products. In other words, the mass and the charge are balanced on both sides of the reaction.
Coefficient
Coefficients are used to balance chemical equations. A coefficient is a number placed in front of a chemical symbol or formula. It shows how many atoms or molecules of the substance are involved in the reaction.
Prefixes
a word, letter, or number placed before another.
PHYSICAL PROPERTIES: A property (as color, hardness, boiling point) of matter not involving in its manifestation a chemical change
Malleable
Able to be hammered or pressed permanently out of shape without breaking or cracking.
Ductile
Able to be drawn out into a thin wire. / Able to be deformed without losing toughness; pliable, not brittle.
State
A state of matter is one of the distinct forms in which matter can exist. Four states of matter are observable in everyday life: solid, liquid, gas, and plasma.
Solubility
The ability to be dissolved, especially in water.
Conductivity
The degree to which a specified material conducts electricity, calculated as the ratio of the current density in the material to the electric field that causes the flow of current. It is the reciprocal of the resistivity.
WATER QUALITY: Water quality can be thought of as a measure of the suitability of water for a particular use based on selected physical, chemical, and biological characteristics.
Hard water
Hard water is water that has high mineral content (in contrast with "soft water"). Hard water is formed when water percolates through deposits of limestone, chalk or gypsum[1] which are largely made up of calcium and magnesium carbonates, bicarbonates and sulfates. Iron oxides or iron carbonates can give a reddish brown colouration to hard water deposits
Filtration
FILTRATION: the action or process of filtering something.
Soft water
Soft water, water that is free from dissolved salts of such metals as calcium, iron, or magnesium, which form insoluble deposits such as appear as scale in boilers or soap curds in bathtubs and laundry equipment
Coliforms
Coliform bacteria are defined as Rod shaped Gram-negative non-spore forming and motile or non-motile bacteria which can ferment lactose with the production of acid and gas when incubated at 35–37°C
Dissolved oxygen
Dissolved oxygen (DO) is the amount of oxygen that is present in water. Water bodies receive oxygen from the atmosphere and from aquatic plants. Running water, such as that of a swift moving stream, dissolves more oxygen than the still water of a pond or lake.
CHEMICAL PROPERTIES: A property or characteristic of a substance that is observed during a reaction in which the chemical composition or identity of the substance is changed.
Substance
Mixtures
MIXTURE: A substance made by mixing other substances together.
Heterogenous
A heterogeneous mixture is simply any mixture that is not uniform in composition
Homogenous
A homogeneous mixture is a mixture in which the composition is uniform throughout the mixture.
Pure Substance
A pure substance is a sample of matter with both definite and constant composition and distinct chemical properties.
Acid/Base/Neutral
Acid
Neutral
An object is neutral when it is not positively or negatively charged. ... This is because all atoms have equal numbers of positively charged protons and negatively charged electrons, leading to overall neutral charge. All ions are charged.
Base
Base, in chemistry, any substance that in water solution is slippery to the touch, tastes bitter, changes the colour of indicators (e.g., turns red litmus paper blue), reacts with acids to form salts, and promotes certain chemical reactions (base catalysis). Examples of bases are the hydroxides of the alkali and alkaline earth metals (sodium, calcium, etc.) and the water solutions of ammonia or its organic derivatives (amines).
Law of conservation of mass
In physics and chemistry, the law of conservation of mass or principle of mass conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as the system's mass cannot change, so quantity can neither be added nor be removed.
FAMILY/GROUP: Elements in the same column, or group, of the periodic table have the same number of valence electrons in their outer energy level. This gives them many similar properties.
Compounds
Metal
METAL: a solid material that is typically hard, shiny, malleable, fusible, and ductile, with good electrical and thermal conductivity
Multivalent Metals
Transition metals capable of having different charges and forming compounds in different proportions are called multivalent metals, or multiple-charge cations.
Alkaline Metals
Alkaline Earth Metals
The alkaline earth metals are six chemical elements in group 2 of the periodic table. They are beryllium, magnesium, calcium, strontium, barium, and radium. The elements have very similar properties: they are all shiny, silvery-white, somewhat reactive metals at standard temperature and pressure.
Any of the elements lithium, sodium, potassium, rubidium, cesium, and francium, occupying Group IA of the periodic table. They are very reactive, electropositive, monovalent metals forming strongly alkaline hydroxides.
Binary
In materials chemistry, a binary phase or binary compound is a chemical compound containing two different elements. Some binary phase compounds are molecular, e.g. carbon tetrachloride. More typically binary phase refers to extended solids.
COMPOUNDS: A chemical compound is a chemical substance composed of many identical molecules composed of atoms from more than one element held together by chemical bonds
Metalloid
A metalloid is a type of chemical element which has a preponderance of properties in between, or that are a mixture of, those of metals and nonmetals. There is no standard definition of a metalloid and no complete agreement on which elements are metalloids.
Non Metal
In chemistry, a nonmetal is a chemical element that mostly lacks the characteristics of a metal. Physically, a nonmetal tends to have a relatively low melting point, boiling point, and density.
Period/Row
A period in the periodic table is a row of chemical elements. All elements in a row have the same number of electron shells. Each next element in a period has one more proton and is less metallic than its predecessor. Arranged this way, groups of elements in the same column have similar chemical and physical properties, reflecting the periodic law. For example, the halogens lie in the second-last column (group 17) and share similar properties, such as high reactivity and the tendency to gain one electron to arrive at a noble-gas electronic configuration. As of 2020, a total of 118 elements have been discovered and confirmed.
Halogen
Any of the elements fluorine, chlorine, bromine, iodine, and astatine, occupying group VIIA (17) of the periodic table. They are reactive nonmetallic elements that form strongly acidic compounds with hydrogen from which simple salts can be made.
Noble gases
Any of the seven chemical elements that make up Group 18 (VIIIa) of the periodic table. The elements are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), radon (Rn), and oganesson (Og). The noble gases are colourless, odourless, tasteless, nonflammable gases. They traditionally have been labeled Group 0 in the periodic table because for decades after their discovery it was believed that they could not bond to other atoms; that is, that their atoms could not combine with those of other elements to form chemical compounds.
Diatomic Atom
Diatomic molecules are molecules composed of only two atoms, of the same or different chemical elements. The prefix di- is of Greek origin, meaning "two". If a diatomic molecule consists of two atoms of the same element, such as hydrogen or oxygen, then it is said to be homonuclear.
Product/Reaction
Product
In chemistry, a product is a substance that is formed as the result of a chemical reaction. In a reaction, starting materials called reactants interact with each other. After passing through a high energy transition state (achieving the activation energy for a reaction), the chemical bonds between the reactants are broken and rearranged to yield one or more products.
Reactant
a substance that takes part in and undergoes change during a reaction.
Combustion
Combustion, or burning, is a high-temperature exothermic redox chemical reaction between a fuel and an oxidant, usually atmospheric oxygen, that produces oxidized, often gaseous products, in a mixture termed as smoke
Precipitate
cause (an event or situation, typically one that is bad or undesirable) to happen suddenly, unexpectedly, or prematurely.
Synthesis
Chemical synthesis, the construction of complex chemical compounds from simpler ones. It is the process by which many substances important to daily life are obtained. It is applied to all types of chemical compounds, but most syntheses are of organic molecules.
Decomposition
Chemical decomposition, or chemical breakdown, is the process or effect of simplifying a single chemical entity (normal molecule, reaction intermediate, etc.) into two or more fragments.[1] Chemical decomposition is usually regarded and defined as the exact opposite of chemical synthesis. In short, the chemical reaction in which two or more products are formed from a single reactant is called a decomposition reaction.
Single displacement
A single replacement reaction, sometimes called a single displacement reaction, is a reaction in which one element is substituted for another element in a compound. When a replacement reaction occurs, a new aqueous compound and a different pure element will be generated as products.
Double displacement
Double replacement reactions—also called double displacement, exchange, or metathesis reactions occur when parts of two ionic compounds are exchanged, making two new compounds.
INDICATOR: a thing, especially a trend or fact, that indicates the state or level of something.
pH Scale
Values can be markedly different from one aqueous solution to another. So chemists defined a new scale that succinctly indicates the concentrations of either of these two ions. pH is usually (but not always) between 0 and 14, If pH < 7, then the solution is acidic, If pH = 7, then the solution is neutral and if pH > 7, then the solution is basic.
This is also known as the pH scale
Chemical change tests
There are 7 main ways to tell if a chemical change is occurring,
gas bubbles, Formation of precipitate, Color change, Temperature change, Production of light, volume change and change in taste or smell.
BOND: A chemical bond is a lasting attraction between atoms, ions or molecules that enables the formation of chemical compounds. The bond may result from the electrostatic force of attraction between oppositely charged ions as in ionic bonds or through the sharing of electrons as in covalent bonds. The strength of chemical bonds varies considerably; there are "strong bonds" or "primary bonds" such as covalent, ionic and metallic bonds, and "weak bonds" or "secondary bonds" such as dipole–dipole interactions, the London dispersion force and hydrogen bonding.
Ion
an atom or molecule with a net electric charge due to the loss or gain of one or more electrons.
Ionic compound
Two-element compounds are usually ionic when one element is a metal and the other is a non-metal.
Polyatomic ion
A molecular ion is a covalently bonded set of two or more atoms, or of a metal complex, that can be considered to behave as a single unit and that has a net charge that is not zero. Unlike a molecule, which has a net charge of zero, this chemical species is an ion.
Ion tests
Chemical tests are simply reactions whose products give visual clues as to the reactants. for example if universal indicator is turned red it means there is an H+ ion in the substance being tested or if a gas turns limewater milky then a calcium carbonate precipitate has been produced we use this reaction to show that the gas was carbon dioxide.
Cation
a positively charged ion, i.e. one that would be attracted to the cathode in electrolysis.
Anion
An anion has more electrons than protons, consequently giving it a net negative charge. For an anion to form, one or more electrons must be gained, typically pulled away from other atoms with a weaker affinity for them. The number of electrons gained, and so the charge of the ion, is indicated after the chemical symbol, e.g. chlorine (Cl) gains one electron to become Cl-, whilst oxygen (O) gains two electrons to become O2-.
Covalent bond
Covalent bond, in chemistry, the interatomic linkage that results from the sharing of an electron pair between two atoms. The binding arises from the electrostatic attraction of their nuclei for the same electrons. A covalent bond forms when the bonded atoms have a lower total energy than that of widely separated atoms.