Select 按钮应设置网页中的文本。怎么办？
我在使用功能按钮时遇到问题。我只知道java应用程序，我正在努力学习HTML和JavaScript。我想用这个按钮将条件语句中的文本设置到网页上，条件基于选择框Select 按钮应设置网页中的文本。怎么办？,select,combobox,Select,Combobox,我在使用功能按钮时遇到问题。我只知道java应用程序，我正在努力学习HTML和JavaScript。我想用这个按钮将条件语句中的文本设置到网页上，条件基于选择框 <!DOCTYPE html> <!-- To change this license header, choose License Headers in Project Properties. To change this template file, choose Tools | Templates and ope
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<TITLE>P-Block Chemical Reactions</TITLE>
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<CENTER><FONT FACE="TIMES NEW ROMAN" COLOR="GREEN" size="50"><b><u>P-Block Chemical Reactions</u></b></font>
<br><br><br><h2>Structure of P-Block</h2><br>
<img src="http://2.bp.blogspot.com/-HNGbTyDrWso/UAGMqI2uY6I/AAAAAAAAAC0/mSWX5ZivvDk/s1600/Use%252Bnowwwww-723799.jpg">
<br></center>
<br>
<form>
<select id="Groups" name="Groups" >
<option value="1">Group 13</option>
<option value="2">Group 14</option>
<option value="3">Group 15</option>
<option value="4">Group 16</option>
<option value="5">Group 17</option>
<option value="6">Group 18</option></select>
<button onClick="gr();">See</button></form>
<script type="text/javascript">
function gr()
{
var s = document.getElementById('Groups');
var g = s.options[s.selectedIndex].value;
if (g === 1)
{
document.write("<b><h3>Chemical Reactions for GROUP 13 :</h3></b><br>
< ul type = "disc" >
< li > Reaction with O < sub > 2 < /sub> <br>
Boron is unreactive in crystalline form.Aluminium forms a very thin oxide layer on the surface which protects the metal from further attack. < br > < br >
2E(s) + 3O < sub > 2 < /sub>(g) → 2E<sub>2</sub > O < sub > 3 < /sub>(s)
(E = element) < br > < br >
< li > Reaction with N < sub > 2 < /sub><br>
With dinitrogen at high temperature these elements form nitrides. < br > < br >
2E(s) + N < sub > 2 < /sub>(g) → 2EN(s)
(E = element) < br > < br >
< li > Reaction with acids and alkalies < br >
Boron does not react with acids and alkalies even at moderate temperature, but aluminium dissolves in mineral acids and aqueous alkalies and thus shows amphoteric character. < br > Aluminium dissolves in dilute HCl and liberates dihydrogen. < br > < br >
2Al(s) + 6HCl(aq) → 2Al < sup > 3 + < /sup>(aq) + 6Cl<sup>-</sup > (aq) < br > < br >
However, concentrated nitric acid renders aluminium passive by forming a protective oxide layer on the surface. < br > < br >
Aluminium also reacts with aqueous alkali and liberates dihydrogen. < br > < br >
2Al(s) + 2NaOH(aq) + 6H < sub > 2 < /sub>O(l) → 2Na<sup>+</sup > [Al(OH) < sub > 4 < /sub>]<sup>-</sup > (aq) + 3H < sub > 2 < /sub>(g) <br><br>
< li > Reaction with halogens < br >
These elements react with halogens to form trihalides (except TlI < sub > 3 < /sub>).<br><br>
2E(s) + 3X < sub > 2 < /sub>(g) → 2EX<sub>3</sub > (s) & nbsp; & nbsp; & nbsp; & nbsp; (X = F, Cl, Br, I)
< /ul>");
}
else if (item === 2)
{
document.write("<b><h3>Chemical Reactions for GROUP 14 :</h3></b><br>
< ul type = "disc" >
< li > Reaction with O < sub > 2 < /sub> <br>
All members when heated in oxygen form oxides.There are mainly two types of oxides, i.e., monoxide and dioxide of formula MO and MO < sub > 2 < /sub> respectively. SiO only exists at high temperature. Oxides in higher Oxidation states of elements are generally more acidic than those in lower oxidation states.<br><br> The dioxides : CO<sub>2</sub > , SiO < sub > 2 < /sub> and GeO<sub>2</sub > are acidic, whereas SnO < sub > 2 < /sub> and PbO<sub>2</sub > are amphoteric in nature.Among monoxides, CO is neutral, GeO is distinctly acidic whereas SnO and PbO are amphoteric. < br > < br >
< li > Reaction with water < br >
Carbon, silicon and germanium are not affected by water.Tin decomposes steam to form dioxide and dihydrogen gas. < br > < br >
Sn + 2H < sub > 2 < /sub>O → SnO<sub>2</sub > + 2H < sub > 2 < /sub> <br><br>
Lead is unaffected by water, probably because of a protective oxide film formation. < br > < br >
< li > Reaction with halogen < br >
These elements can form halides of formula MX < sub > 2 < /sub> and MX<sub>4</sub > (where X = F, Cl, Br, I).Except carbon, all other members react directly with halogen under suitable condition to make halides.Most of the MX < sub > 4 < /sub> are covalent in nature. The central metal atom in these halides undergoes sp<sup>3</sup > hybridisation and the molecule is tetrahedral in shape.Exceptions are SnF < sub > 4 < /sub> and PbF<sub>4</sub > , which are ionic in nature. < br > PbI < sub > 4 < /sub> does not exist because Pb-I bond initially formed during the reaction does not release enough energy to unpair 6s<sub>2</sub > electrons and excite one of them to higher orbital to have four unpaired electrons around lead atom.Heavier members Ge to Pb are able to make halides of formula MX < sub > 2 < /sub>. Stability of dihalides increases down the group. Considering the thermal and chemical stability, GeX<sub>4</sub > is more stable than GeX < sub > 2 < /sub>, whereas PbX<sub>2</sub > is more than PbX < sub > 4 < /sub>. Except CCl<sub>4</sub > , other tetrachlorides are easily hydrolysed by water because the central atom can accomodate the lone pair of electrons from oxygen atom of water in d orbital.
< /ul><br><br>");
}
else if (item === 3)
{
document.write("<b><h3>Chemical Reactions for GROUP 15 :</h3></b><br>
< ul type = "disc" >
< li > Reaction with Hydrogen < br >
All the elements of Group 15 form hydrides of the type EH < sub > 3 < /sub> where E = N, P, As, Sb or Bi.<br> The stability of hidrides decreases from NH<sub>3</sub > to BiH < sub > 3 < /sub> which can be observed from their bond dissociation enthalpy. Consequently,the reducing character of the hydrides increases. Ammonia is only a mild reducing agent while BiH<sub>3</sub > is the strongest reducing agent amongst all the hydrides.Basicity also decreases in the order NH < sub > 3 < /sub> > PH<sub>3</sub > & gt; AsH < sub > 3 < /sub> > SbH<sub>3</sub > & ge; BiH < sub > 3 < /sub>.<br><br>
< li > Reaction with Oxygen < br >
All these elements form two types of oxides: E < sub > 2 < /sub>O<sub>3</sub > and E < sub > 2 < /sub>O<sub>5</sub > .The oxide in the higher oxidation state of the element is more acidic than that of lower oxidation state.Their acidic character decreases down the group.The oxides of the type E < sub > 2 < /sub>O<sub>3</sub > of nitrogen and phosphorus are purely acidic, that of arsenic and antimony amphoteric and those of bismuth is predominantaly basic. < br > < br >
< li > Reaction with Halogen < br >
These elements react to form two series of halides: EX < sub > 3 < /sub> and EX<sub>5</sub > .Nitrogen does not form pentahalide due to non - availability of the d - orbitals in its valence shell.Pentahalides are more covalent than trihalides.All the trihalides of these elements except those of nitrogen are stable.In case of nitrogen, only NF < sub > 3 < /sub> is known to be stable. Trihalides except BiF<sub>3</sub > are predominantly covalent in nature. < br > < br >
< li > Reaction with Metal < br >
All these elements react with metals to form their binary compounds exhibiting - 3 oxidation state, such as, Ca < sub > 3 < /sub>N<sub>2</sub > (Calcium nitride), Ca < sub > 3 < /sub>P<sub>2</sub > (Calcium phosphide), Na < sub > 3 < /sub>As<sub>2</sub > (Sodium arsenide), Zn < sub > 3 < /sub>Sb<sub>2</sub > (Zinc antimonide) and Mg < sub > 3 < /sub>Bi<sub>2</sub > (Magnesium bismuthide). < br > < br >
< /ul>");
}
else if (item === 4)
{
document.write("<b><h3>Chemical Reactions for GROUP 16 :</h3></b><br>
< ul type = "disc" >
< li > Reaction with Hydrogen < br >
All the elements of Group 16 form hydrides of the type H < sub > 2 < /sub>E (E = S, Se, Te, Po). Their acidic character increases from H<sub>2</sub > O to H < sub > 2 < /sub>Te. The increse in acidic character can be explained in terms of decrease in bond (H-E) dissociation enthalpy down the group. Owing to the decrease in bond (H-E) dissociation enthalpy down the group, the thermal stability of hydrides also decreases from H<sub>2</sub > O to H < sub > 2 < /sub>Po. All the hydrides except water possess reducing property and this character increases from H<sub>2</sub > S to H < sub > 2 < /sub>Te.<br><br>
< li > Reaction with Oxygen < br >
All these elements form oxides of the EO < sub > 2 < /sub> and EO<sub>3</sub > types where E = S, Se, Te or Po.Ozone (O < sub > 3 < /sub>) and sulphur dioxide (SO<sub>2</sub > ) are gases while selenium dioxide (SeO < sub > 2 < /sub>) is solid. Reducing property of dioxide decreases from SO<sub>2</sub > to TeO < sub > 2 < /sub>. SO<sub>2</sub > is reducing while TeO < sub > 2 < /sub> is an oxidising agent. Besides EO<sub>2</sub > type, sulphur, selenium and tellurium also form EO < sub > 3 < /sub> type oxides (SO<sub>3</sub > , SeO < sub > 3 < /sub>, TeO<sub>3</sub > ).Both types of oxides are acidic in nature. < br > < br >
< li > Reaction with Halogen < br >
Elements of Group 16 form a large number of halides of the type, EX < sub > 6 < /sub>, EX<sub>4</sub > and EX < sub > 2 < /sub> where E is an element of the group and X is a halogen. The stability of the halides decreases in the order F<sup>-</sup > & gt; Cl < sup > - < /sup> > Br<sup>-</sup > & gt; I < sup > - < /sup>. Amongst hexahalides, hexafluorides are the only stable halides. All hexafluorides are in gaseous nature. They have octahedral structure. Sulphur hexafluoride, SF<sub>6</sub > is exceptionally stable for steric reasons. < br >
Amongst tetrafluorides, SF < sub > 4 < /sub> is a gas, SeF<sub>4</sub > a liquid and TeF < sub > 4 < /sub> a solid. These fluorides have sp<sup>3</sup > d hybridisation and thus, have trigonal bipyramidal structures in which one of the equatorial positions is occupied by a lone pair of electrons.This geometry is also regarded as see - saw geometry. < br >
All elements except selenium form dichlorides and dibromides.These dihalides are formed by sp < sup > 3 < /sup> hybridisation and thus, have tetrahedral structure. The well known monohalides are dimeric in nature. Examples are S<sub>2</sub > F < sub > 2 < /sub>, S<sub>2</sub > Cl < sub > 2 < /sub>, S<sub>2</sub > Br < sub > 2 < /sub>, Se<sub>2</sub > Cl < sub > 2 < /sub> and Se<sub>2</sub > Br < sub > 2 < /sub>. These dimeric halides undergo disproportionation as given below: <br><br>
2Se < sub > 2 < /sub>Cl<sub>2</sub > → SeCl < sub > 4 < /sub> + 3Se <br><br>
< /ul>");
}
else if (item === 5)
{
document.write("<li><b><h3>Chemical Reactions for GROUP 17 :</h3></b><br>
< ul type = "disc" >
< li > Reaction with Hydrogen < br >
They all react with hydrogen to give hydrogen halides but affinity for hydrogen decreases from fluorine to iodine.They dissolve in water to form hydrohali acids.The acidic strength of these acids varies in the order: HF & lt; HCl & lt; HBr & lt; HI.The stability of these halides decreases down the group due to decrease in bond (H - X) dissociation enthalpy in the order: H - F & gt; H - Cl & gt; H - Br & gt; H - I. < br > < br >
< li > Reaction with Oxygen < br >
Halogens form many oxides with oxygen but most of them are unstable.Fluorine forms two oxides OF < sub > 2 < /sub>, O<sub>2</sub > F < sub > 2 < /sub>. However, only OF<sub>2</sub > is thermally stable at 298 K.These oxides are essentially oxygen fluorides because of the higher electronegativity of fluorine than oxygen.Both are strong fluorinating agents.O < sub > 2 < /sub>F<sub>2</sub > oxidises plutonium to PuF < sub > 6 < /sub> and the reaction is used in removing plutonium as PuF<sub>6</sub > from spent nuclear fuel. < br >
Chlorine, bromine and iodineChlorine, bromine and iodine form oxides in which the oxidation
states of these halogens range from + 1 to + 7. A combination of kinetic and thermodynamic factors lead to the generally decreasing order of stability of oxides formed by halogens, I & gt; Cl & gt; Br.The higher oxides of halogens tend to be more stable than the lower ones. < br >
Chlorine oxides, Cl < sub > 2 < /sub>O, ClO<sub>2</sub > , Cl < sub > 2 < /sub>O<sub>6</sub > and Cl < sub > 2 < /sub>O<sub>7</sub > are highly reactive oxidising agents and tend to explode.ClO < sub > 2 < /sub> is used as a bleaching agent for paper pulp and textiles and in water treatment.<br>
The bromine oxides, Br < sub > 2 < /sub>O, BrO<sub>2</sub > , BrO < sub > 3 < /sub> are the least stable halogen oxides (middle row anomally) and exist only at low temperatures. They are very powerful oxidising agents. The iodine oxides, I<sub>2</sub > O < sub > 4 < /sub>, I<sub>2</sub > O < sub > 5 < /sub>, I<sub>2</sub > O < sub > 7 < /sub> are insoluble solids and
decompose on heating.I < sub > 2 < /sub>O<sub>5</sub > is a very good oxidising agent and is
used in the estimation of carbon monoxide. < br > < br >
< li > Reaction with Metals < br >
Halogens react with metals to form metal halides.For example, bromine reacts with magnesium to give magnesium bromide. < br > < br >
Mg(s) + Br < sub > 2 < /sub>(l) → MgBr<sub>2</sub > (s) < br > < br >
The ionic character of the halides decreases in the order MF & gt;
MCl & gt; MBr & gt; MI where M is a monovalent metal.If a metal exhibits
more than one oxidation state, the halides in higher oxidation
state will be more covalent than the one in lower oxidation state.
For example, SnCl < sub > 4 < /sub>, PbCl<sub>4</sub >
, SbCl < sub > 5 < /sub> and UF<sub>6</sub >
are more covalent than SnCl < sub > 2 < /sub>
, PbCl < sub > 2 < /sub>, SbCl<sub>3</sub >
and UF < sub > 4 < /sub> respectively.<br><br>
< li > Reaction with Halogens < br >
Halogens combine amongst themselves to form number of compounds known as interhalogens of the types XX < sup > ` < /sup>, XX<sup>`</sup > < sub > 3 < /sub>, XX<sup></sup > < sub > 5 < /sub> and XX<sup>`</sup > < sub > 7 < /sub> where X is a larger size halogen and X<sup>`</sup > is a smaller size halogen. < br > For example: & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; I < sub > 2 < /sub> + Cl<sub>2</sub > & nbsp; → 2ICl < br > & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; & nbsp; (equimolar) < br > < br >
< /ul>");
}
}
</script>
</body>
</html>
P-嵌段化学反应
P-嵌段化学反应
P-块的结构
第13组
第14组
第15组
第16组
第17组
第18组
看见
函数gr（）
{
var s=document.getElementById（'Groups'）；
var g=s.options[s.selectedIndex].value；
如果（g==1）
{
记录。写下（“第13组的化学反应：
与O2的反应
硼以晶体形式不反应。铝在表面形成一层非常薄的氧化层，保护金属免受进一步的侵蚀。
2E（s）+3O2（g）→ 2E2 O3（s）
（E=元素）
与N2的反应
这些元素在高温下与二氮一起形成氮化物。
2E（s）+N2（g）→ 2EN(s)
（E=元素）
- 与酸和碱的反应
硼即使在中等温度下也不会与酸和碱发生反应，但铝溶于矿物酸和水性碱中，因此表现出两性特征。
铝溶于稀HCl并释放出二氢。
2Al（s）+6HCl（aq）→ 2Al3+（aq）+6Cl-（aq）
然而，浓硝酸通过在表面形成一层保护性氧化层使铝钝化。
铝还与水性碱反应并释放出二氢。
2Al（s）+2NaOH（aq）+6H2O（l）→ 2Na+[Al（OH）4]-（aq）+3H2（g）
- 与卤素的反应
这些元素与卤素反应形成三卤化物（TlI3除外）。
2E（s）+3X2（g）→ 2EX3（s）（X=F，Cl，Br，I）
”；
}
否则如果（项目===2）
{
记录。写下（“第14组的化学反应：
与O2的反应
当在氧气中加热时，所有成员形成氧化物。主要有两种氧化物，即分子式为MO和MO2的一氧化碳和二氧化物。SiO仅在高温下存在。元素的高氧化态的氧化物通常比低氧化态的氧化物更酸性。
二氧化合物：CO2，SiO>2和GeO2是酸性的，而SnO2和PbO2是两性的。在一氧化物中，CO是中性的，GeO是明显酸性的，而SnO和PbO是两性的。
- 与水的反应
碳、硅和锗不受水的影响。锡分解蒸汽形成二氧化碳和二氢气体。
Sn+2H2O→ SnO2+2H2
铅不受水的影响，可能是因为形成了保护性氧化膜。
- 与卤素的反应
这些元素可形成式MX2和MX4的卤化物（其中X=F，Cl，Br，I）。除碳外，所有其他成员在适当条件下直接与卤素反应生成卤化物。大多数MX4本质上是共价的。这些卤化物中的中心金属原子经过sp3杂化，分子呈四面体形状。SnF4和PbF4除外，它们本质上是离子。
PbI4不存在，因为最初在反应过程中形成的Pb-I键没有释放足够的能量来解封6s2电子，并将其中一个电子激发到更高的轨道，使铅原子周围有四个未配对的电子。较重的Ge-Pb元素能够生成式MX2的卤化物。二卤化物的稳定性考虑到热稳定性和化学稳定性，GeX4比GeX2更稳定，而PbX2比PbX4更稳定。除了CCl4外，其他四氯化硅很容易被水水解，因为中心原子可以容纳d轨道中水氧原子的孤对电子。
”；
}
否则如果（项目===3）
{
记录。书写（“第15组的化学反应：
- 与氢的反应
第15族的所有元素形成EH3类型的氢化物，其中E=N、P、As、Sb或Bi。
从NH3到BiH，氢化物的稳定性降低<