Alkali metal is a term that refers to six elements: lithium (Li), sodium (Na), potassium (K), rubidium (Rb), caesium (Cs), and francium (Fr). These elements make up group 1 of the periodic table of elements. They all form singly charged positive ions, and are extremely reactive. They react violently with water, forming hydroxides and releasing hydrogen gas and heat. Caesium and francium are the most reactive and lithium is the least.
Alkali earth metal is a term that refers to six elements: beryllium (Be), magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba), and radium (Ra). These elements make up group 2 of the periodic table of elements. They all exhibit a single oxidation state, +2. They are all light and very reactive. Barium and radium are the most reactive and beryllium is the least.
To denote slightly soluble metal oxides chemists formerly used the term "earth". The oxides of barium, strontium, and calcium resemble alumina (Al2O3), a typical "earth", but form alkaline mixtures with water. For this reason barium, strontium, and calcium were called alkaline earth metals. This name has now been extended to include all of the elements of group 2.
Bravais lattice is a set of points constructed by translating a single point in discrete steps by a set of basis vectors. The French crystallographer Auguste Bravais (1811-1863) established that in three-dimensional space only fourteen different lattices may be constructed. All crystalline materials recognised till now fit in one of these arrangements. The fourteen three-dimensional lattices, classified by crystal system, are shown to the bottom.
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Crystal system
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Bravais lattices
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cubic a=b=c α=β=γ=90° |
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simple cubic
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body-centered cubic
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face-centered cubic
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tetragonal a=b≠c α=β=γ=90° |
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simple tetragonal
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body-centered tetragonal
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orthorhombic a≠b≠c α=β=γ=90° |
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simple orthorhombic
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base-centered orthorhombic
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body-centered orthorhombic
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face-centered orthorhombic
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monoclinic a≠b≠c α=γ=90°≠β |
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simple monoclinic
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base-centered monoclinic
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hexagonal a=b≠c α=β=90° γ=120° |
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hexagonal
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rhombohedral a=b=c α=β=γ≠90° |
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rhombohedral
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triclinic a≠b≠c α≠β≠γ≠90° |
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triclinic
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Generalic, Eni. "/tab." Croatian-English Chemistry Dictionary & Glossary. 29 June 2022. KTF-Split. {Date of access}. <https://glossary.periodni.com>.
Glossary
Periodic Table
