Chapter 8 Vocab List

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Vocab 8a Chemical property The ability or inability of a substance to combine with or change into one or more new substances. - flammability - reactivity (rusting, tarnishing, etc.) Physical property Properties that can be observed without changing the substance Conductivity Ability to transfer heat or electricity Chemical change The change of one or more substances into other substances - happens when old bonds are broken between atoms and new ones form - Can't be reversed with a physical change Physical change The properties of a substance change, but the identity of the substance doesn't - changes of state - dissolving Antoine Lavoisier (1743-1794) Showed mass is conserved in chemical reactions - he created a precise balance and measured substances before and after reactions to see that the mass had not changed Law of Conservation of MassThe total mass before a chemical reaction is the same as the total mass after the reaction Chemical formulas Used to represent molecules or ionic compounds - H 2O

9. Diatomic elements

- elements that bond with themselves - two atoms - H2, N2, O2, F2, Cl2, Br2, I2

10. Compounds

Molecules made of 2 or more different elements - H2O, NaCl, CO2

11. Chemical bonding 12. Chemical bond 13. Valence electrons 14. Ionic bonds 15. Forming positive ions

Vocab 8b The joining of atoms to form new substances. The attraction that holds two atoms together - caused by gaining, losing, or sharing electrons Electrons in the outer energy level of an atom that are involved in chemical bonds Bonds that form when valence electrons are transferred from one atom to another When an atom loses an electron, it has a positive charge because it has one more proton than the number of electrons it has - metals tend to lose electrons because they only have one or two valence electrons (it takes less energy than from fuller outer levels)

16. Forming negative ions

17. Ionic compounds

18. Covalent bonds

19. Molecules 20. Electron-dot diagram 21. Complex molecules

22. Metallic bond

When an atom gains an electron, it has a negative charge because it has one more electron than the number of protons it has - Nonmetals tend to gain electrons because they almost have a full set of valence electrons - "ide" means it's a negative ion (like flouride) - Opposite ions (a metal and a nonmetal) combine - No overall charge because ions balance each other out - ions form a crystal lattice structure - properties - brittle, solid, high melting points, water soluble Bonds that form when atoms share pairs of Electrons in the outer energy level of an atom that - Usually occur when an ionic bond would take too much energy (like 2 nonmetals) Two or more atoms joined with covalent bonds Dots represent valence electrons (like He: ) Have more than 2 atoms bonded together - Carbon is often the "backbone" of complex molecueles - examples - sugar, soap, proteins attraction between positive metal ions and the electrons around them - electrons can move throughout the metal - properties - malleable, ductile, good conductors