اجابات التقييم الاسبوعى الاسبوع الاول فى الساينس لغات للصف الاول الاعدادى الترم الثانى 2025

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Ministry of Education

Central Administration for Curriculum Development

Science Consultant Office

First Year of Middle School

First Term 2024/2025

Science

Unit One: Elements and Chemical Bonds

Lesson One: Weekly Test

What is meant by each one of the following:

1. Metallic bond:
• A chemical bond formed between metal atoms due to the attraction between positive metal ions and a cloud of delocalized electrons.
2. Alloys:
• A mixture of two or more metals, or a metal and a non-metal, designed to improve the properties of the base metal.
3. Recycling:
• The process of converting waste materials into new materials and objects, reducing the need for raw materials and minimizing environmental impact.

How do you differentiate between each of the following:

1. Phosphorus – Iron in terms of:
• a) Metallic luster: Iron has a metallic luster, while phosphorus does not.
• b) Malleable and ductile: Iron is malleable and ductile, while phosphorus is brittle.
• c) Conductivity of heat and electricity: Iron is a good conductor, while phosphorus is a poor conductor.
• d) Melting point: Iron has a high melting point, while phosphorus has a low melting point.
2. Sodium and Graphite in terms of:
• Metallic luster: Sodium has a metallic luster, while graphite is opaque.
3. Sulfur and Copper in terms of:
• Malleable and ductile: Copper is malleable and ductile, while sulfur is brittle.
4. Silver and Phosphorus in terms of:
• Conductivity of electric current: Silver is a good conductor, while phosphorus is a poor conductor.

Complete the following sentences:

1. The outermost energy level of metals contains less than 4 electrons, while non-metals contain more than 4 electrons.
2. Element (A), with its outermost energy level (M) containing two electrons is a metal, while element (B) with its outermost energy level (L) containing six electrons is a non-metal.
3. All metals are solids except for mercury, which is a liquid.
4. All non-metals are bad conductors of electricity except for graphite, which is a good conductor of electricity.
5. All non-metals are solid materials such as sulfur, gaseous materials such as oxygen, and the only liquid is bromine.
6. The atoms of solid metals are arranged in a structure known as a metallic lattice.
7. The metallic bond is formed due to the attraction between positive metal ions and the cloud of valence negative electrons surrounding it.
8. The bronze alloy is composed of tin at 5% and copper at 95%.
9. The bronze alloy is used in manufacturing medals and statues.
10. The bronze alloy is characterized by being more durable than copper and resistant to rust.

 

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