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20 Cards in this Set
- Front
- Back
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What did Mendeleev contribute to the periodic table in the beginning stages? |
He arranged the elements by increasing atomic mass. He noticed that similarities between their chemical properties began to appear at regular intervals. He left 3 spaces for elements yet to be discovered. |
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What did Mosely contribute to the periodic table? |
He arranged the elements by atomic number, making the properties fit together much better. |
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What is Periodic Law? |
Physical and chemical properties of the elements are periodic functions of the atomic number. |
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Describe where the different blocks lie on the periodic table. |
Block s is group one and two. Block d is groups 3-12. Block p is groups 13-18. Block f is the lanthanide and actinide series. |
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What group are the alkali metals in? What are they like? |
They are in group 1. They are very reactive and thus are not found in pure form in nature. As you go down the group, they melt at lower temperatures. |
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What group are alkaline earth metals in? What are they like? |
They are in group 2. They are denser and stronger than alkali metals, but not as reactive as them. |
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What group are the halogens in? What are they like? |
Group 17. They are VERY reactive. |
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What group are the noble gases in? What are they like? |
They are in group 18. They are not reactive. |
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What is the atomic radii? |
It is the radius of an atom. |
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Why does the atomic radii decrease across a period? Why does it increase down a group? |
It decreases across a period because there are more protons to pull the electrons in tighter. It increases down a group because more levels are being added. |
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What is ionization energy? |
It is the energy that it takes to remove an electron from an atom. |
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Why does the ionization energy increases across a period? Why does it decrease down a group? |
Across a period, more protons are being added, providing a stronger pull on the electrons and thus more energy is needed to pull them away. Down a group, electrons are spread out farther due to the larger number of levels. |
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What is electron affinity? |
It is the energy that is produced when an electron is added to an atom. |
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Why does electron affinity increase across a period? Why does it decrease down a group? |
Across a period, more electrons are there to allow more energy to be produced. Down a group, the cloud is bigger so there is less energy to be put out. |
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What is a cation? |
An ion with a positive charge. It has lost an electron. |
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What is an anion? |
An ion with a negative charge. It has gained an electron. |
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What is a valence electron? Where is it? |
It is an electron that can be lost, gained, or shared. It is on the highest energy level that is incomplete. |
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What is electronegativity? |
It is the ability to attract electrons from other atoms. |
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How do you find the number of valence electrons a neutral element will have? |
Subtract ten from the group number. |
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How do you find the atomic radius of an atom? |
You put two identical atoms together and measure the distance between the nuclei. It is half of that distance. |
