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  2. What Is an Element in Chemistry? Definition and Examples -...

    www.thoughtco.com/definition-of-element-chemistry-604452

    A chemical element is a substance that cannot be further broken down by any chemical reaction. Each element has a unique number of protons in its atom. For example, a hydrogen atom has 1 proton, while a carbon atom has 6 protons. Varying the number of electrons in an atom of an element produces ions. Changing the number of neutrons produces ...

  3. What Is a Chemical Element? Definition and Examples - ThoughtCo

    www.thoughtco.com/what-is-a-chemical-element-604297

    Radioactive decay can produce different isotopes of the same element or a lighter element. When the term "chemical element" is used, it can refer to a single atom of that atom or to any pure substance consisting only of that type of iron. For example, an iron atom and a bar of iron are both elements of the chemical element.

  4. What Is an Element Symbol? Chemistry Definition - ThoughtCo

    www.thoughtco.com/definition-of-element-symbol-604453

    An element symbol is a one- or two-letter abbreviation for a chemical element name. When a symbol consists of two letters, the first letter is always capitalized, while the second letter is lowercase. Element symbols also can refer to alchemy symbols for the elements or to the symbols used to describe isotopes.

  5. Reactivity Definition in Chemistry - ThoughtCo

    www.thoughtco.com/reactivity-definition-4147073

    Updated on August 17, 2019. In chemistry, reactivity is a measure of how readily a substance undergoes a chemical reaction. The reaction can involve the substance on its own or with other atoms or compounds, generally accompanied by a release of energy. The most reactive elements and compounds may ignite spontaneously or explosively.

  6. The Definition of Atomic Mass or Weight in Chemistry - ThoughtCo

    www.thoughtco.com/definition-of-atomic-mass-weight-604375

    Atomic Mass or Weight Definition. Atomic mass, which is also known as atomic weight, is the average mass of atoms of an element, calculated using the relative abundance of isotopes in a naturally occurring element. Atomic mass indicates the size of an atom. Although technically the mass is the sum of the mass of all the protons, neutrons, and ...

  7. Periodicity Definition in Chemistry - ThoughtCo

    www.thoughtco.com/definition-of-periodicity-604600

    In the context of chemistry and the periodic table, periodicity refers to trends or recurring variations in element properties with increasing atomic number. Periodicity is caused by regular and predictable variations in element atomic structure. Mendeleev organized elements according to recurring properties to make a periodic table of elements ...

  8. Oxidation Definition and Example in Chemistry - ThoughtCo

    www.thoughtco.com/definition-of-oxidation-in-chemistry-605456

    A classic example of the old definition of oxidation is when iron combines with oxygen to form iron oxide or rust. The iron is said to have oxidized into rust. The chemical reaction is: 2 Fe + O 2 → Fe 2 O 3. The iron metal is oxidized to form the iron oxide known as rust. Electrochemical reactions are great examples of oxidation reactions.

  9. Mass Number Definition and Examples - ThoughtCo

    www.thoughtco.com/definition-of-mass-number-604564

    Examples. 3717 Cl has a mass number of 37. Its nucleus contains 17 protons and 20 neutrons. The mass number of carbon-13 is 13. When a number is given following an element name, this is its isotope, which basically states the mass number. To find the number of neutrons in an atom of the isotope, simply subtract the number of protons (atomic ...

  10. Main Group Elements Definition - ThoughtCo

    www.thoughtco.com/definition-of-main-group-elements-605876

    Updated on September 03, 2019. In chemistry and physics, the main group elements are any of the chemical elements belonging to the s and p blocks of the periodic table. The s-block elements are group 1 (alkali metals) and group 2 (alkaline earth metals). The p-block elements are groups 13-18 (basic metals, metalloids, nonmetals, halogens, and ...

  11. What Is a Chemical Symbol? Definition and Examples - ThoughtCo

    www.thoughtco.com/definition-of-chemical-symbol-604909

    H is the chemical symbol for hydrogen. C is the chemical symbol for carbon. Si is the chemical symbol for silicon. Uno was the element symbol for hassium. Uno stands for "unniloctium" or "element 108." Chemical symbols are found on the periodic table and are used when writing chemical formulas and equations.