Questions and Answers
How are elements in the periodic table arranged?
The elements in the periodic table are arranged in order of atomic (proton) number and so that elements with similar properties are in columns, known as groups.
Why is this table called a periodic table?
The table is called a periodic table because similar properties occur at regular intervals.
What similarities do elements in the same group have?
Elements in the same group in the periodic table have the same number of electrons in their outer shell, giving them similar chemical properties.
Before the discovery of protons, neutrons and electrons, how did scientists classify elements?
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What was the problem of the early periodic tables?
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How did Dimitri Mendeleev overcome problems?
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What did Mendeleev do when the elements were discovered?
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What did the knowledge of isotopes make possible?
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What are metals?
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What are non-metals?
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Where are metals found on the periodic table?
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Where are non-metals found on the periodic table?
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What are the properties of metals?
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What are the properties of non-metals?
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Why are Group 0 elements called noble gases?
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What is the arrangement of Group 0 elements?
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What are the properties of Group 0 elements?
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What are Group 1 metals also known as?
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What are the properties of Group 1 metals?
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What is the trend of Group 1 metals?
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How do alkali metals form ionic compounds with non-metals?
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What happens when alkali metals (Group 1) react with water?
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What happens when alkali metals (Group 1) react with chlorine?
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What happens when alkali metals (Group 1) react with oxygen?
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What are Group 7 elements known as?
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What is the trend in Group 7?
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Describe the halogen fluorine.
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Describe the halogen chlorine.
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Describe the halogen bromine.
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Describe the halogen iodine.
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Compare transition metals with Group 1 metals.
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What trends are observed in halogens?
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What is the concept of displacement of halogens?
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Study Notes
Periodic Table Arrangement
- Elements are ordered by atomic (proton) number, creating groups with similar properties.
- The term "periodic" reflects the recurrence of similar properties at regular intervals.
Group Characteristics
- Elements in the same group share the same number of outer shell electrons, leading to similar chemical behaviors.
Early Element Classification
- Prior to proton, neutron, and electron discovery, classification was based on atomic weights.
- Early periodic tables often placed elements incorrectly due to strict adherence to atomic weights.
Mendeleev's Contribution
- Dimitri Mendeleev improved classification by leaving gaps for undiscovered elements and adjusting order based on properties.
- His predictions for undiscovered elements were later confirmed with actual discoveries.
Isotopes and Atomic Weight
- Understanding isotopes clarified discrepancies within atomic weight-based ordering.
Metals vs. Non-Metals
- Metals form positive ions and are located on the left and bottom of the periodic table.
- Non-metals do not form positive ions and are found towards the right and top.
Properties of Metals
- Metals are strong, malleable, good conductors of heat/electricity, and have high melting/boiling points.
- All metals exhibit metallic bonding.
Properties of Non-Metals
- Non-metals lack metallic bonding, are dull, brittle, and often gaseous at room temperature.
- They generally do not conduct electricity and have lower densities.
Noble Gases (Group 0)
- Group 0 elements, or noble gases, are unreactive with stable electron arrangements, mostly consisting of colorless monatomic gases.
- Their boiling points rise with atomic mass due to increased intermolecular forces.
Alkali Metals (Group 1)
- Group 1 elements, known as alkali metals, have one outer shell electron, making them highly reactive.
- Reactivity increases down the group, alongside decreasing melting/boiling points and increasing atomic mass.
Alkali Metals and Reactions
- Alkali metals react vigorously with water, producing hydrogen gas and metal hydroxides.
- Reactions with chlorine yield white metal chlorides and become more vigorous down the group.
- They also form metal oxides upon reacting with oxygen, exhibiting varied products.
Halogens (Group 7)
- Halogens possess seven outer shell electrons and form diatomic molecules, showing colored vapors.
- Reactivity decreases down the group, while melting/boiling points and relative molecular masses increase.
Specific Halogen Properties
- Fluorine: Very reactive, poisonous yellow gas.
- Chlorine: Fairly reactive, dense poisonous green gas.
- Bromine: Dense, red-brown volatile liquid that is also poisonous.
- Iodine: Appears as dark grey crystalline solid or purple vapor.
Transition Metals vs. Group 1
- Transition metals are less reactive than alkali metals but are stronger, denser, and typically have higher melting points.
- Transition elements often form colored compounds and have variable ionic charges.
Displacement Reactions in Halogens
- More reactive halogens can displace less reactive ones in aqueous solutions, demonstrating the trend in reactivity.
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Description
Explore the arrangement of the periodic table, including how elements are classified by atomic number and their group characteristics. Dive into the contributions of Mendeleev and the significance of isotopes in understanding atomic weights.