lecture 3 - periodic table Flashcards
(16 cards)
How are elements arranged in the periodic table?
Elements are arranged by increasing the atomic number.
What are groups and periods in the periodic table?
• Groups: Vertical columns with similar chemical properties.
• Periods: Horizontal rows showing repeating trends.
Define atomic radius.
The distance from the nucleus to the outermost electron.
What is the trend for atomic radius in groups and periods?
• Increases down a group (more electron shells).
• Decreases across a period (greater nuclear charge pulls electrons closer).
Define electronegativity.
The ability of an atom to attract bonding electrons.
How does electronegativity change across a period and down a group?
• Increases across a period.
• Decreases down a group.
Which element is the most electronegative?
Fluorine (F), with a value of 4.0.
What is the difference between polar and non-polar covalent bonds?
• Non-polar: Electrons shared equally.
• Polar: Unequal sharing due to different electronegativities.
What is ionization energy?
The minimum energy required to remove an electron from an atom or ion.
What are the trends in ionization energy?
• Increases across a period.
• Decreases down a group.
Explain Aufbau’s, Hund’s, and Pauli’s principles for electron configuration.
• Aufbau: Electrons fill the lowest energy levels first.
• Hund’s Rule: Single electrons fill degenerate orbitals before pairing.
• Pauli Exclusion: No two electrons in an orbital can have the same spin.
How do noble gas notations simplify electron configurations?
Use the nearest noble gas to represent core electrons.
• Example for Mg: [Ne] 3s^2 .
What ions do alkali metals (Group 1) form?
They lose 1 electron to form +1 ions (e.g., Na⁺).
Which group forms ions by gaining 1 electron?
Group 17 (Halogens) form -1 ions (e.g., Cl⁻).
What type of bond forms in NaCl?
Ionic bond, where Na loses an electron and Cl gains one.
Why is Cs more electropositive than Na?
Cs’s outermost electron is farther from the nucleus, reducing attraction and making it easier to lose.
