如何计算自由基的化合价?
要构造离子化合物的分子式,我们必须首先了解结合生成离子化合物的正离子和负离子的化合价。因此,我们将从离子价开始。离子的化合价等于它的电荷。如果离子具有一个单位电荷,则其化合价为一,称为一价离子。当一个离子含有两个电荷单位时,其化合价为二,称为二价离子。如果一个离子具有三个电荷单位,则它的化合价为三,称为三价离子。请记住,阳离子带有正电荷,因此具有正价;阴离子带有负电荷,因此具有负价。
什么是激进分子?
自由基的行为就像一个带有正电荷或负电荷的单个原子,它们被定义为一个原子或一组相同或不同元素的原子,显示出带有电荷的原子的性质。由于它们形成化学式的结合能力,它们具有自己的结合能力。
例如:
NH 4+ , Na + , NO 3- , SO 4 2-
离子或自由基的化合价
The valency of any element is defined as a measure of its combining capacity and the number of electrons that must be gained or lost by an atom to obtain a stable electronic configuration.
前 18 个元素在不同壳层中写入电子配置的规则是计算壳层中存在的最大电子数 = 2n 2的公式, 其中 n = 1, 2, 3(即轨道号)。
对于不同的壳,最大电子分布为,
- K 壳 n = 1 = 2n 2 = 2(1) 2 = 2
- L 壳 n = 2 = 2n 2 = 2(2) 2 = 8
- M 壳 n = 3 = 2n 2 = 2(3) 2 = 18
- N 壳 n = 4 = 2n 2 = 2(4) 2 = 32
带电离子或自由基的化合价等于它们上存在的电荷量。根据自由基或离子上存在的电荷,它们分为三种:
- 单价离子- 具有一价的离子或具有一个单位电荷的离子,称为单价离子。例如 - 氢离子 (H + )、锂离子 (Li + )、铵离子 (NH 4 + )、溴离子 (Br – )、氢氧根离子 (OH – ) 等。
- 二价离子 -具有两个化合价的离子或具有两个单位电荷的离子,称为二价离子。例如 - 镁离子 (Mg 2+ )、钙离子 (Ca 2+ )、锌离子 (Zn 2+ )、氧化物离子 (O 2- )、硫化物离子 (S 2- ) 等。
- 三价离子——三价离子或三价离子,称为三价离子。例如-铝离子(Al 3+ )、铁离子(Fe 3+ )、氮化物离子(N 3- )、磷酸根离子(PO 4 3- )等。
常见离子或自由基的化合价
以下是常见单原子阳离子的表格表示: Valency Element Ion of the Element Hydrogen H+ Lithium Li+ Sodium Na+ Potassium K+ Cesium Cs+ Silver Ag+ Beryllium Be2+ Magnesium Mg2+ Calcium Ca2+ Cadmium Cd2+ Nickel Ni2+ Strontium Sr2+ Barium Ba2+ Aluminum Al3+1+ (Monovalent) 2+ (Divalent) 3+ (Trivalent)
以下是常见单原子阴离子的表格表示: Valency Element Ion of the Element Hydride H– Fluoride F– Chloride Cl– Bromide Br– Iodide I– Oxide O2- Sulfide S2- Nitride N3- Phosphide P3-1- (Monovalent) 2- (Divalent) 3- (Trivalent)
以下是常见多原子自由基的表格表示: Valency Radical Symbol IonMonovalent [1] Hypochlorite ClO ClO1- Chlorite ClO2 ClO21- Chlorate ClO3 ClO31- Perchlorate ClO4 ClO41- Hypobromite BrO BrO1- Bromite BrO2 BrO21- Bromate BrO3 BrO31- Perbromate BrO4 BrO41- Hypoiodite IO IO1- Iodite IO2 IO21- Iodate IO3 IO31- Periodate IO4 IO41- Hydroxide OH OH1- Nitrite NO2 NO21- Nitrate NO3 NO31- Bicarbonate [Hydrogen carbonate] HCO3 HCO31- Bisulfite [Hydrogen sulfite] HSO3 HSO31- Bisulfate [Hydrogen sulfate] HSO4 HSO41- Dihydrogen phosphate H2PO4 H2PO41- Cyanide CN CN1- Cyanate CNO CNO1- Thiocyanate SCN SCN1- Permanganate MnO4 MnO41- Acetate C2H3O2 C2H3O21- Divalent [2] Peroxide O2 O22- Carbonate CO3 CO32- Sulfite SO3 SO32- Sulfate SO4 SO42- Thiosulfate S2O3 S2O32- Biphosphate [Hydrogen phosphate] HPO4 HPO42- Chromate CrO4 CrO42- Dichromate Cr2O7 Cr2O72- Oxalate C2O4 C2O42- Trivalent [3] Phosphite PO3 PO33- Phosphate PO4 PO43-
示例问题
问题 1:找出 H 2 S 分子和 PO 4 3-离子中存在的原子数。
回答:
In H2S molecule, there are two atoms of hydrogen (H) and one atom of sulphur (S). Hence three atoms of H and S totally present in H2S molecule. However, in PO43- ion, there are one atom of phosphorus (P )and four atoms of oxygen (O) hence five atoms of P and O totally present in PO43- ion.
问题 2:计算给出的每个物种的分子量,
H 2 O、Cl 2 、CO 2和 CH 4
回答:
The molecular masses of the given species are determined as shown below:
- The molecular mass of H2O = 2 × atomic mass of H + 1 × atomic mass of oxygen = 2 × 1 + 1 × 16 = 2 + 16 = 18 u.
- The molecular mass of Cl2 = 2 × atoms atomic mass of Cl = 2 × 35.5 = 71 u.
- The molecular mass of CO2 = 1 × atoms atomic mass of C + 2 × atomic mass of O = 1 × 12 + 2 × 16 = 12 + 32 = 44 u.
- The molecular mass of CH4 = 1 × atoms atomic mass of C + 4 × atomic mass of H = 1 × 12 + 4 × 1 = 16 u.
问题3:什么是多原子离子?举个例子。
回答:
Polyatomic ions are the ions that contain more than one atom but they are as a single unit. Examples of polyatomic ions are : CO32-, H2PO4–.
问题 4:写出氧化钠和氯化铝的化学式。
回答:
The formula of Sodium oxide can be calculated as,
Valency of Sodium = 1
Valency of Oxygen = 2
Hence, the formula of sodium oxide is Na2O.
And the formula of Aluminum chloride can be calculated as,
Valency of Aluminum = 3
Valency of chloride = 1
Hence, the formula of Aluminum chloride is AlCl3.
问题 5:如果 1 摩尔碳 (C) 原子重 12 克,那么 1 个碳原子的质量是多少?
回答:
Given that,
One mole of carbon (C) = 12 g weighs
one mole of carbon atoms = 6.022 × 1023
Molecular mass of carbon atoms = An atom of carbon mass = 12 g
Hence, mass of 1 carbon atom = 12 / 6.022 × 1023 = 1.99 ×10-23 g