وفّر 50٪ من خلال الاشتراك السنوي في مجرة واحصل على تصفح لا محدود لأفضل محتوى عربي على الإنترنت.
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هي قوى الجذب قصيرة المدى الموجودة بين جزيئات المواد غير المشحونة كهربائياً (المحايدة) بشكل عام، وتعد من أضعف أنواع التفاعلات الموجودة على المستوى الجزيئي أو الذري في الطبيعة، حيث تجذب أو تسبب تنافر الجزيئات المجاورة لبعضها بعضها سواء في الغازات أو السوائل العضوية والمواد الصلبة.
تم تسمية هذه القوى تيمناً بالفيزيائي الهولندي يوهانس ديديريك فان دير فالس، الذي افترض لأول مرة في عام 1873 وجود هذه القوى بين الجزيئات، أثناء تطويره نظرية لحساب خصائص الغازات الحقيقية.
إذ لاحظ فاندرفالس أن الإلكترونات الموزعة بشكل غير متساوٍ في جميع أنحاء ذرة أو جزيء، تميل إلى التحرك باستمرار وتشكل ثنائي قطب مؤقت، ويشكل ثنائي القطب المؤقت هذا المتكون في ذرة واحدة ثنائي قطب مؤقت آخر في الذرة المجاورة، وتستمر العملية هذه ما يسبب الالتصاق والجذب أو التنافر المؤقت بين الأجسام.
هو رابطة أو جزيء لدى نهاياته شحنة معاكسة للنهاية الأخرى. أحد أهم الأمثلة عن ثنائيات الأقطاب الرابطة في الماء، التي تربط بين الهيدروجين الموجب مع الأوكسجين السالب.
توجد قوى فاندرفالس بالطبيعة والصناعة بشكل كبير، ومن الأمثلة عنها ما يلي:
هناك ثلاثة أنواع رئيسية لقوى فاندرفالس وهي كالتالي:
من أهم صفات قوى فاندرفالس ما يلي:
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