chemistry(for exam)

1)electrons in an atom are aranged in shells.The distribution of electrons in the various shells is called electronic arrangement

在原子中，電子以殼層排列，電子在各層中的排列稱為電子排佈。

2)electrolytes are compounds which allow electricity to pass through them only when molten or in aqueous solution.There is chemical decomposition during the conduction.

當一個化合物在融熔狀態或溶於水成為溶液時可以導電，該化合物稱為電解質。當導通電流時有化學分解發生。

3)An ion is an atom or a group of atoms having an overall electric charge.

離子由單一的原子或原子團(即多於一個原子)所形成，離子帶有不為零的電荷。

4)all metals form ions:they usually form cations,Some non-metals form ions:most of these are anions

所有金屬都形成離子，通常形成正離子，部份非金屬會形成離子，大多數為陰離子。

5)Ionic bond is the strong non-directional electrostatic force of attraction between oppositely charged ions.An ionic bond is formed by the transfer of one or moreelectrons from one atom to another

離子鍵是帶相反電性的離子間的無方向性的強大吸引力，離子鍵是由一粒或多粒電子由一個原子轉移到另一個原子所形成的。

6) a molecule is the smallest part of an element or a compound which can exist on its own under ordinary conditions.

分子是在常溫常壓下元素或化合物的最細小而又可以單獨存在的粒子。