The image provided is a visual representation of the periodic table along with some key questions and answers related to it. Below, I will explain each question and its corresponding answer in detail:
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1. How many elements are there?
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Answer: 118
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Explanation: The periodic table currently contains
118 elements. These elements are organized based on their atomic number, which increases from left to right and top to bottom. As of now, all 118 elements have been discovered or synthesized, and they are included in the standard periodic table.
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2. What is the periodic table?
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Answer: A chart that organizes elements by atomic number and shared properties.
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Explanation: The periodic table is a tabular arrangement of chemical elements, ordered by their atomic number (the number of protons in the nucleus). Elements are grouped into rows (periods) and columns (groups) based on their atomic structure and chemical properties. This organization helps highlight patterns and trends in element behavior, such as reactivity, electronegativity, and ionization energy.
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3. Who invented the periodic table?
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Answer: Dmitri Mendeleev
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Explanation: The modern periodic table was first developed by
Dmitri Mendeleev, a Russian chemist, in 1869. Mendeleev arranged the elements in order of increasing atomic mass and noticed recurring patterns in their chemical and physical properties. He left gaps for undiscovered elements and even predicted their properties, which were later confirmed when those elements were discovered.
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4. What are the periodic table trends?
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Answer: Electronegativity, ionization energy, atomic radius, electron affinity.
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Explanation: Periodic table trends refer to the predictable changes in certain properties of elements as you move across a period or down a group. Here are the main trends:
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Electronegativity: Increases across a period (left to right) and decreases down a group.
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Ionization Energy: Increases across a period (left to right) and decreases down a group.
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Atomic Radius: Decreases across a period (left to right) and increases down a group.
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Electron Affinity: Generally increases across a period (left to right), but there are exceptions due to orbital stability.
These trends are primarily influenced by the nuclear charge (number of protons) and the distance of electrons from the nucleus.
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5. Why are noble gases so inert?
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Answer: They have stable electron configurations.
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Explanation: Noble gases (Group 18 of the periodic table, including helium, neon, argon, etc.) are highly unreactive because their outermost electron shells are completely filled. This stable electron configuration makes them resistant to forming chemical bonds with other elements. For example, helium has a full 1s orbital, while neon has a full 2s and 2p subshell. This stability explains why noble gases are often referred to as "inert."
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Summary of Key Points:
1. There are
118 elements in the periodic table.
2. The periodic table is a chart that organizes elements by atomic number and shared properties.
3. Dmitri Mendeleev is credited with inventing the periodic table.
4. Periodic table trends include electronegativity, ionization energy, atomic radius, and electron affinity.
5. Noble gases are inert because they have stable electron configurations.
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Final Answer:
\boxed{118} (for the number of elements)
\boxed{\text{A chart that organizes elements by atomic number and shared properties}} (for what the periodic table is)
\boxed{\text{Dmitri Mendeleev}} (for who invented the periodic table)
\boxed{\text{Electronegativity, ionization energy, atomic radius, electron affinity}} (for periodic table trends)
\boxed{\text{They have stable electron configurations}} (for why noble gases are inert)
Parent Tip: Review the logic above to help your child master the concept of periodic table of elements worksheet answers.
