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| one twelfth of the mass of a carbon-12 atom |
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| elements that are good conductors of heat and electric current |
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| the patterns of repeating properties displayed by elements in the periodic table |
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| a column of elements in the periodic table |
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| elements that are poor conductors of heat and electric current |
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| an arrangement of elements in columns, based on a set of properties that repeat from row to row |
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| elements with properties that fall between those of metals in nonmetals |
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| a row in the periodic table of elements. |
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| elements that form a bridge between elements on the left and right sides of the periodic table |
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| the elements in group 1A of the periodic table, not including hydrogen |
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| an ion with a positive charge |
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| the elements in group 7A of the periodic table |
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| the elements in group 8A of te periodic table |
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| the elements in group 2A of the periodic table |
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| the force that holds atoms or ions together as a unit |
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Definition
| an atom or group of atoms that has a + or - charge |
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| an ion with a negative charge |
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| a diagram of an atom, ion or molecule in wich each dot represents a valence electron |
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| the force that holds anions and cations together |
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| a mixture of two or more elements, at least one of which is a metal, that has the characteristic properties of a metal |
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| solids whose particle are arranged in a lattice structure |
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| a neutral group of atoms that are joined together by one or more covalent bonds |
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| notation that shows what elements a compound contains and the ratio of the atoms or ions of these elements in the compound |
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Definition
| a covalent bond in which electrons are not shared equally |
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Definition
| a chemical bond in which two atoms share a pair of valence electrons |
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Definition
| the attraction between a metal cation and the shared electrons that surround it |
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Term
| How did Mendeleev organize the elements in his periodic table? |
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Definition
| In rows in order of increasing mass so that elements wit similar properties were in the same column |
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Term
| What evidence helped verify the usefullness of Mendeleev's table |
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Definition
| The close match between Mendeleev's predictions and te actual properties of new elements showed how useful his periodic table could be |
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Term
| How is the modern periodic table organized? |
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Definition
| Elements are arranged by increasing atomic number. (# of protons) Each row is a period. Properties of elements repeat in a predictable way when atomic numbers are used to arrange elements into groups (columns) |
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Term
| What does the atomic mass of an element depend on? |
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Definition
| The distribution of an elements isotopes in nature and the masses of those isotopes |
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Term
| What categories are used to classify elements on te periodic table? |
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Definition
| Metals, Non metals, or metalloids |
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Term
| How do properties vary across a period in the periodic table? |
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Definition
| They become less metallic and more non metallic as you move from left to right |
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| Why do elements in a group have similar properties? |
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Definition
| They have the same number of valence electrons. |
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| What are some of the properties of the A groups in te periodic table? |
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Definition
1A Alkali metals are extremely reactive
2A Alkaline earth metals
7A Halogens
8A Noble gasses |
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Term
| When is an atom unlikely to react? |
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Definition
| When the highest occupied energy level of an atom is filled with electrons, the atom is stable and not likely to react. |
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Term
| What is one way in which elements can achieve stable electron configurations? |
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Definition
| Transfer of electrons between atoms (ionic bonds) |
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Term
| How does the structure of an ionic compound affect its properties? |
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Definition
| The properties of an ionic compound can be explained by the strong attraction among ions in the crystal lattice. ( Brittle ) |
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Term
| How are atoms held together in a covalent bond? |
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Definition
| The attractions between the shared electrons and the protons in each nucleus hold the atoms together in a covalent bond |
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Term
| What factors determine whether a moldcule is polar? |
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Definition
| The type of atoms in a molecule and its shape are factors that determine whether a molecule is polar or non polar |
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Term
| How do attractions between polar molecules compare to attractions between nonpolar molecules? |
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Definition
| They are stronger. Example is the strong attraction between water molecules that leads to it large energy required to boil. |
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Term
| What are the forces that give a metal its structure as a solid? |
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Definition
| The cations in a metal form a lattic that isw held in place by strong metallic bonds between the cations and the surrounding valence electrons. |
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Term
| How do metallic bonds produce some of the typical properties of metals? |
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Definition
| The mobility of electrons within a metal lattice explains some of the properties of metals |
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Term
| How are te properties of alloys controlled? |
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Definition
| Scientists can design alloys with specific properties by varying the types and amounts of elements in an alloy. |
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