Lithium Atomic Number

Learning Objective

Lithium atomic number and mass
  1. Lithium, a chemical element with the symbol Li, is one of the highly reactive alkali metals of group 1 with an atomic number 3 in the periodic table. Lithium is not found in a free state in nature due to its high reactivity behavior so that it is abstracted from different compounds (mostly from salts). Lithium is the lightest metal ever found.
  2. Oct 23, 2018 The lightest known metal can also lighten your mood. Lithium, atomic number 3, is an element of many uses. It's used in the manufacture of aircraft and in certain batteries.

Li I Ground State 1s 2 2s 2 S 1 / 2 Ionization energy 43487.150 cm-1 (5.391719 eV) Ref. K87 Li II Ground State 1s 2 1 S 0 Ionization energy 610078 cm-1 (75.6400 eV) Ref. DM01-1 (75.6400 eV) Ref.

  • Determine the relationship between the mass number of an atom, its atomic number, its atomic mass, and its number of subatomic particles

Key Points

  • Neutral atoms of each element contain an equal number of protons and electrons.
  • The number of protons determines an element’s atomic number and is used to distinguish one element from another.
  • The number of neutrons is variable, resulting in isotopes, which are different forms of the same atom that vary only in the number of neutrons they possess.
  • Together, the number of protons and the number of neutrons determine an element’s mass number.
  • Since an element’s isotopes have slightly different mass numbers, the atomic mass is calculated by obtaining the mean of the mass numbers for its isotopes.


  • atomic massThe average mass of an atom, taking into account all its naturally occurring isotopes.
  • mass numberThe sum of the number of protons and the number of neutrons in an atom.
  • atomic numberThe number of protons in an atom.

Atomic Number

Neutral atoms of an element contain an equal number of protons and electrons. The number of protons determines an element’s atomic number (Z) and distinguishes one element from another. For example, carbon’s atomic number (Z) is 6 because it has 6 protons. The number of neutrons can vary to produce isotopes, which are atoms of the same element that have different numbers of neutrons. The number of electrons can also be different in atoms of the same element, thus producing ions (charged atoms). Best hidden gps tracker for person. For instance, iron, Fe, can exist in its neutral state, or in the +2 and +3 ionic states.

Lithium Atomic Number

Mass Number

An element’s mass number (A) is the sum of the number of protons and the number of neutrons. The small contribution of mass from electrons is disregarded in calculating the mass number. This approximation of mass can be used to easily calculate how many neutrons an element has by simply subtracting the number of protons from the mass number. Protons and neutrons both weigh about one atomic mass unit or amu. Isotopes of the same element will have the same atomic number but different mass numbers.

Scientists determine the atomic mass by calculating the mean of the mass numbers for its naturally-occurring isotopes. Often, the resulting number contains a decimal. For example, the atomic mass of chlorine (Cl) is 35.45 amu because chlorine is composed of several isotopes, some (the majority) with an atomic mass of 35 amu (17 protons and 18 neutrons) and some with an atomic mass of 37 amu (17 protons and 20 neutrons).

Given an atomic number (Z) and mass number (A), you can find the number of protons, neutrons, and electrons in a neutral atom. For example, a lithium atom (Z=3, A=7 amu) contains three protons (found from Z), three electrons (as the number of protons is equal to the number of electrons in an atom), and four neutrons (7 – 3 = 4).

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The Element Lithium

[Click for Isotope Data]

Atomic Number: 3

Atomic Weight: 6.941

Lithium Mass Number

Melting Point: 453.65 K (180.50°C or 356.90°F)

Boiling Point: 1615 K (1342°C or 2448°F)

Density: 0.534 grams per cubic centimeter

Phase at Room Temperature: Solid

Element Classification: Metal

Period Number: 2

Group Number: 1

Lithium Atomic Number Of Protons

Group Name: Alkali Metal

What's in a name? From the Greek word for stone, lithos.

Say what? Lithium is pronounced as LITH-ee-em.

History and Uses:

Lithium was discovered in the mineral petalite (LiAl(Si2O5)2) by Johann August Arfvedson in 1817. It was first isolated by William Thomas Brande and Sir Humphrey Davy through the electrolysis of lithium oxide (Li2O). Today, larger amounts of the metal are obtained through the electrolysis of lithium chloride (LiCl). Lithium is not found free in nature and makes up only 0.0007% of the earth's crust.

Many uses have been found for lithium and its compounds. Lithium has the highest specific heat of any solid element and is used in heat transfer applications. It is used to make special glasses and ceramics, including the Mount Palomar telescope's 200 inch mirror. Lithium is the lightest known metal and can be alloyed with aluminium, copper, manganese, and cadmium to make strong, lightweight metals for aircraft. Lithium hydroxide (LiOH) is used to remove carbon dioxide from the atmosphere of spacecraft. Lithium stearate (LiC18H35O2) is used as a general purpose and high temperature lubricant. Lithium carbonate (Li2CO3) is used as a drug to treat manic depression disorder.

Lithium reacts with water, but not as violently as sodium.

Estimated Crustal Abundance: 2.0×101 milligrams per kilogram

Estimated Oceanic Abundance: 1.8×10-1 milligrams per liter

Lithium Atomic Number Mass

Number of Stable Isotopes: 2 (View all isotope data)

Ionization Energy: 5.392 eV

Oxidation States: +1

Electron Shell Configuration:



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