Term
| Who discovered a pattern to the elements? |
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Definition
- Dmitri Mendeleev
- a Russian chemist
- in 1869
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Term
How had Mendeleev arranged elements when he noticed a pattern?
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Definition
| in order of increasing atomic mass |
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Term
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Definition
something that occurs or repeats at regular intervals
Mendeleev found that elements' properties followed a pattern that repeated every seven elements |
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Term
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Definition
| Repeating chemical and physical properties of elements change periodically with the elements' atomic numbers |
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Term
| What property is used to arrange elements in the periodic table? |
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Definition
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Term
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Definition
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Term
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Definition
A row of elements (horizontal - from left to right on the periodic table)
Properties (physical & chemical) in a row follow a repeating pattern as you move across the period. |
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Term
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Definition
a column of elements (vertical - from top to bottom on the period table)
elements in a group share chemical properties |
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Term
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Definition
- shiny (luster)
- ductile (can be pulled into a thin wire)
- good conductors of electric currents & thermal energy
- malleable (can be flattened with a hammer & will not break)
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Term
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Definition
- NOT malleable or ductile
- Not shiny
- Poor conductors of thermal energy & electric currents
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Term
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Definition
| have properties of metals & nonmetals |
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Term
| What happens as you move from left to right acorss a row? |
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Definition
| the elements become less metallic |
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Term
| How are properties of the elements in a group similar? |
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Definition
| The atoms of the elements have the same number of electrons in their outer energy level |
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Term
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Definition
Group contains: Metals
Electrons in the outer level: 1
Reactivity: very reactive
Other shared properties: softness, color of silver, shininess, low density |
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Term
Alkaline-Earth Metals
Group 2 |
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Definition
Group contains: metals
Electrons in the outer level: 2
Reactivity: very reactive but less reactive than alkali metals
Other shared properties: color of silver, high densities than alkali metal |
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Term
Transition Metals
Group 3-12 |
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Definition
Group contains: metals
Electrons in the outer level: 1 or 2
Reactivity: less reactive than alkaline-earth metals
Other shared properties: shininess; good conductors of thermal energy and electric current; higher densities and melting points than elements in group 1 or 2 (except for mercury) |
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Term
| Why are alkali metals more reactive than transition metals? |
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Definition
| It is easier for atoms of alkali metals to lose their outer electron than for atoms of transition metals to lose their outer electrons. Therefore, alkali metals are more reactive than transition metals. |
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Term
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Definition
Group contains: one metalloid & five metals
Electrons in the outer level: 3
Reactivity: reactive
Other shared properties: solids at room temperature |
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Term
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Definition
Group contains: one nonmetals, two metalloids, and three metals
Electrons in the outer level: 4
Reactivity: varies among the elements
Other shared properties: solids at room temperature |
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Term
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Definition
Group contains: two nonmetals, two metalloids, and two metals
Electrons in the outer level: 5
Reactivity: varies among the elements
Other shared properties: solids at room temperature (except for nitrogen) |
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Term
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Definition
Group contains: three nonmetals, one metalloid, and one metal
Electrons in the outer level: 6
Reactivity: reactive
Other shared properties: all but oxygen are solid at room temperaute |
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Term
| Which gases from Groups 15 and 16 make up most of the air you breathe? |
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Definition
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Term
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Definition
Group contains: nonmetals
Electrons in the outer level: 7
Reactivity: very reactive
Other shared properties: poor conductors of electric current; violent reactions with alkali metals to form salts; never in uncombined form in nature |
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Term
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Definition
- one of the elements of Group 17 (on the periodic table)
- contains fluorine, chlorine, bromine, iodine, and astatine
- combine with most metals to form salts
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Term
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Definition
Group contains: nonmetals
Electrons in the outer level: 8 (except helium, which has 2)
Reactivity: unreactive
Other shared properties: colorless; odorless gases at room temperature |
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Term
| Why are noble gases unreactive? |
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Definition
| Atoms of noble gases have a full set of electrons (8) in their outer level |
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Term
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Definition
Electrons in the outer level: 1
Reactivity: reative
Other properties: colorless, odorless gas at room temperature; low density; explosive reactions with oxygen |
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Term
| Why is hydrogen not included in any other group? |
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Definition
| It is set off by itself in the periodic table because the properties do not match the properties of any other group. |
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