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8th Grade Chapter5
Atoms and Bonding
| Question | Answer |
|---|---|
| when an atom loses an electron | it becomes a positive ion |
| each family in the periodic table has its own characteristic properties | based on the number of valence electrons |
| an ionic bond is the attraction between | oppositely charged ions |
| polyatomic ions | ions that are made of more than one atom |
| ionic compounds | form hard, brittle crystals with characteristic shapes |
| ionic compounds conduct electricity | when dissolved in water |
| covalent bond | a chemical bond formed when two atoms share electrons |
| a double bond | two pairs of electrons shared between two atoms |
| s property shared by most molecular compounds | low melting point |
| molecular compounds do not conduct electricity | because they do not break up into ions |
| a covalent bond in which electrons are shared unequally | is polar |
| in a chemical formula for an ionic compound | the positive ion is written first |
| electrons involved in bonding between atoms are | valence electrons |
| the greatest number of valence electrons an atom can have is | 8 |
| what happens when water and oil are poured into the same container | the liquids do not mix |
| ionic compounds are | electrically neutral |
| malleable | means that metals can be rolled into thin sheets or beaten into complex shapes |
| alloy | a mixture that is made of two elements, one that is a metal, and has the properties of metal |
| ad advantage of alloys over pure metals | alloys resist rust |
| steel is an alloy combined with | iron |
| examples of alloys | brass and steel |
| a metal crystal | positive metal ions surrounded by freely moving valence electrons |
| ductile | means that metals can be pulled into thin strands or wires |
| metallic bond | the attraction between a positive metal ion and the electrons surrounding it |
| a strong alloy containing carbon, iron, and another metal like chromium or nickel used to make construction equipment is | steel |
| steel | has strength, is resistant to rust, and does not readily react with water |
| valence electrons | shown on electron dot diagrams, transferred or share in bonding, and are loosely held by the nucleus |