اهلا وسهلا بك فى بوابة الثانوية العامة ... سجل الان

  #1  
قديم 25-09-2013, 11:36 PM
مستر محمد طلعت مستر محمد طلعت غير متواجد حالياً
عضو مجتهد
 
تاريخ التسجيل: Sep 2010
المشاركات: 60
معدل تقييم المستوى: 14
مستر محمد طلعت is on a distinguished road
افتراضي prep 2


Many attempts are made by scientists for classification of elements why?
1-to be easily studied
2-find the relation between elements and their physical and chemical properties.
Mendeleev`s table:
He discovered that the elements were arranged in an ascending order according to their atomic weights from left to right in the horizontal rows.
disadvanges of Mendeleev`s table:
1-He had to make a disturbance in the ascending order of atomic weights for some elements due to putting them in groups which suit their properties.
2-he also would have to deal with the isotopes of one element as different elements because they are different in their atomic weights.
Advantages:
1- Mendeleev predicted the ability of discovering new elements so he left spaces (empty cells) in his table.
2- He corrected the wrong estimated atomic weights of some elements.


Moseley `s table:
1- Moseley rearranged the elements in an ascending order according to their atomic number.
2- Added the inert gases in the (0) zero group.
3- classified each main group into two subgroups (A , where he found differences between their properties
4- he allocated a place below his periodic table for the two groups lanthanides and actinides

What is the scientific principle on which the classification of the elements based on?
• Mendeleev’s periodic table: .................................................. ..................................................
• Moseley’s periodic table............................................. .................................................. ..
Note;
1-Rutherford discovered that the nucleus of atom contains positively charged protons
2-Moseley discovered in the same year after studying the properties of X rays that the periodicity of elements properties is related to their atomic number not their atomic weights.
Modern periodic table:
1-Bohr discovered the main energy levels they are 7.
2-main energy level consists of a number of energy levels known as the energy sublevels.
Description:
1-Elements are classified in the modern periodic table according to
Their atomic numbers the way of filling the energy sublevels with electrons.

 

العلامات المرجعية

أدوات الموضوع
انواع عرض الموضوع

ضوابط المشاركة
لا تستطيع إضافة مواضيع جديدة
لا تستطيع الرد على المواضيع
لا يمكنك اضافة مرفقات
لا يمكنك تعديل مشاركاتك

BB code متاحة
كود [IMG] متاحة
كود HTML معطلة

الانتقال السريع


جميع الأوقات بتوقيت GMT +2. الساعة الآن 12:30 AM.