Questions and Answers
What led Mendeleev to predict that some elements had not been discovered yet?
When he created his periodic table, he saw there were gaps in it and he could predict the characteristics of the elements that should go in those gaps.
What do elements in the same period have in common?
They have the same number of occupied energy levels.
What do elements in the same group have in common?
They have similar chemical properties and the same number of valence electrons.
Why can period 1 contain a maximum number of two elements?
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Which group of elements is the most unreactive, and why?
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Why are halogens extremely reactive?
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With which group are halogens most reactive?
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How do the valence electron configurations of the alkali metals compare with each other?
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Why are the alkaline earth metals less reactive than the alkali metals?
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Why do groups within the main-group elements show similar chemical behavior?
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Explain why the transition metals are sometimes referred to as the d block elements.
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According to scientifically supported theories, how and where did the natural elements form?
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Describe the relationship between a transmutation and a synthetic element.
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Why is a transmutation classified as a nuclear reaction?
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Study Notes
Mendeleev's Predictions
- Mendeleev identified gaps in his periodic table, leading him to predict the existence of undiscovered elements with specific characteristics.
Periods and Groups
- Elements in the same period share the same number of occupied energy levels.
- Elements in the same group exhibit similar chemical properties and have the same number of valence electrons.
Period 1 Constraints
- Period 1 can hold a maximum of two elements due to the s orbital, which accommodates only 2 electrons.
Noble Gases
- Group 8 elements, known as noble gases, are the most unreactive because they have completely filled energy levels.
Reactivity of Halogens
- Halogens are highly reactive since they require only one additional electron for filled energy levels.
- They are most reactive with alkali metals (Group 1).
Alkali Metals' Valence Electrons
- All alkali metals have a valence electron configuration of 1.
Alkaline Earth Metals Reactivity
- Alkaline earth metals are less reactive than alkali metals due to having two electrons in their outer shell, making electron loss more challenging.
Main-Group Elements Behavior
- Similar chemical behavior in main-group elements is due to the same number of valence electrons, which govern reactivity.
Transition Metals
- Transition metals are termed d block elements because their added electrons occupy the d orbitals.
Formation of Natural Elements
- Natural elements formed post-Big Bang as protons, neutrons, and electrons coalesced to create hydrogen, leading to star formation; elements heavier than iron were produced during supernovas.
Transmutation and Synthetic Elements
- Transmutation processes can create synthetic elements, highlighting the connection between them.
Transmutation as a Nuclear Reaction
- Transmutation is classified as a nuclear reaction as it involves the fusion of atomic nuclei, resulting in the formation of heavier atoms.
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Test your knowledge of the periodic table with these flashcards! Each card challenges you on key concepts, such as Mendeleev's predictions and the characteristics of elements in periods and groups. Perfect for students studying chemistry or anyone looking to refresh their understanding of elemental properties.