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  2. Effective atomic number (compounds and mixtures) - Wikipedia

    en.wikipedia.org/wiki/Effective_atomic_number...

    is the fraction of the total number of electrons associated with each element, and Z n {\displaystyle Z_{n}} is the atomic number of each element. An example is that of water (H 2 O), made up of two hydrogen atoms (Z=1) and one oxygen atom (Z=8), the total number of electrons is 1+1+8 = 10, so the fraction of electrons for the two hydrogens is ...

  3. Charge number - Wikipedia

    en.wikipedia.org/wiki/Charge_number

    This is a property of specific subatomic atoms. These elements define the electromagnetic contact between the two elements. A chemical charge can be found by using the periodic table. An element's placement on the periodic table indicates whether its chemical charge is negative or positive. Looking at the table, one can see that the positive ...

  4. Thermodynamic databases for pure substances - Wikipedia

    en.wikipedia.org/wiki/Thermodynamic_databases...

    Row 5. Values of the five parameters for the third C p equation; temperature limit for the equation. Row 6. Number of H T - H 298 equations required. Row 7. Values of the six parameters for the first H T - H 298 equation; temperature limit for the equation, and ΔH° trans for the first phase change. Row 8.

  5. Component (thermodynamics) - Wikipedia

    en.wikipedia.org/wiki/Component_(thermodynamics)

    The number of components represents the minimum number of independent chemical species necessary to define the composition of all phases of the system. [2] Calculating the number of components in a system is necessary when applying Gibbs' phase rule in determination of the number of degrees of freedom of a system.

  6. Formal charge - Wikipedia

    en.wikipedia.org/wiki/Formal_charge

    The formal charge of any atom in a molecule can be calculated by the following equation: = where V is the number of valence electrons of the neutral atom in isolation (in its ground state); L is the number of non-bonding valence electrons assigned to this atom in the Lewis structure of the molecule; and B is the total number of electrons shared ...

  7. Chemical formula - Wikipedia

    en.wikipedia.org/wiki/Chemical_formula

    In chemistry, the empirical formula of a chemical is a simple expression of the relative number of each type of atom or ratio of the elements in the compound. Empirical formulae are the standard for ionic compounds , such as CaCl 2 , and for macromolecules, such as SiO 2 .

  8. Valence (chemistry) - Wikipedia

    en.wikipedia.org/wiki/Valence_(chemistry)

    The valence is the combining capacity of an atom of a given element, determined by the number of hydrogen atoms that it combines with. In methane, carbon has a valence of 4; in ammonia, nitrogen has a valence of 3; in water, oxygen has a valence of 2; and in hydrogen chloride, chlorine has a valence of 1.

  9. List of chemistry mnemonics - Wikipedia

    en.wikipedia.org/wiki/List_of_chemistry_mnemonics

    An atom (or ion) whose oxidation number increases in a redox reaction is said to be oxidized (and is called a reducing agent). It is accomplished by loss of one or more electrons. The atom whose oxidation number decreases gains (receives) one or more electrons and is said to be reduced. This relation can be remembered by the following mnemonics.