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- 4. nother to form a new substance, called synthesis or, alternatively, decomposes into two or more different substances. These processes are called chemical reactions and, in general, are not reversible except by further chemical reactions.
- 5. odorless, colorless, monatomic gases with very low chemical reactivity. The six noble gases that occur naturally are helium (He), neon (Ne), argon (Ar), krypton (Kr), xenon (Xe), and the radioactive radon (Rn).
- 6. s are a group of elements in the periodic table. They are all in the first column of the periodic table. They are extremely reactive.
- 7. chemical formula is a way of expressing information about the proportions of atoms that constitute a particular chemical compound, using a single line of chemical element symbols, numbers, and sometimes also other symbols, such as parentheses, dashes, brackets, commas and plus (+) and minus (−) signs.
- 9. n electron in an outer shell of an atom that can participate in forming chemical bonds with other atoms.
- 10. is the symbolic representation of a chemical reaction in the form of symbols and formulas.
- 11. the results of a chemical reaction
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- 1. ysical changes occur when objects or substances undergo a change that changes the physical form of a composition but not the chemical composition
- 2. conservation states that for any system closed to all transfers of matter and energy, the mass of the system must remain constant over time, as system mass cannot change quantity if it is not added or removed. Hence, the quantity of mass is "conserved" over time.
- 3. substance that takes part in and undergoes change during a reaction.
- 8. - A chemical bond is a lasting attraction between atoms that enables the formation of chemical compounds.