L1_Chem

• Who started grouping elements into triads based on atomic weight averages?

  Dobereiner
• Newlands' law of octaves states that every eighth element has similar properties to the first.
• Who created the first periodic table based on atomic masses?

  Mendeleev
• The modern periodic law states that the physical and chemical properties of elements are periodic functions of their atomic number
• Why is the atomic number considered a fundamental property of an element?

  It equals the number of electrons
• The periodic table arranges elements in groups (vertical columns) and periods (horizontal rows
• What is the primary cause of periodicity in the periodic table?

  Recurrence of similar electronic configuration
• The modern periodic table has 18 groups, which represent the number of electrons in the outermost shell.
• Match the group with its common name:

  Group 1 ↔️ Alkali Metals

  Group 2 ↔️ Alkaline Earth Metals

  Group 17 ↔️ Halogens

  Group 18 ↔️ Noble Gases
• Which groups are considered main or representative elements in the periodic table?

  1, 2, 13-17
• The periods in the periodic table represent the number of shells
• What is atomic size in the periodic table defined as?

  Distance between nucleus and outermost shell
• Increasing the number of shells in an atom increases its size.
• The nuclear charge of an atom is equal to the number of protons
• How does metallic character change across a period from left to right?

  Decreases
• How does non-metallic character change down a group from top to bottom?

  Decreases
• The most reactive metal in the periodic table is Caesium
• Which element is the most reactive non-metal in the periodic table?

  Fluorine
• The melting and boiling points of non-metals increase as you go down the group.
• Across a period, melting points and boiling points typically increase up to group 14 and then decrease
• What is ionisation potential defined as?

  Energy to remove an electron
• Ionisation potential increases across a period from left to right.
• Electronegativity measures the tendency of an atom to attract a shared pair of electrons
• Who developed the scale for measuring electronegativity?

  Linus Pauling
• The atomic number is a unique property of an element because no two elements have the same atomic number.
• The mass number of an element is the sum of the number of protons and neutrons
• Why are electron gain enthalpy values of noble gases positive?

  Stable electronic configuration
• Noble gases have a stable electronic configuration.
• Which period in the periodic table is incomplete?

  Seventh period
• The seventh period of the periodic table is incomplete.
• The p-block elements belong to groups 13 to 18.
• Arrange the following elements in decreasing order of atomic size:

  Na ↔️ Mg

  Mg ↔️ Si

  Si ↔️ S

  S ↔️ Cl
• Electron affinity is the energy released when an electron is added to a neutral gaseous atom.
• What is the energy released when one electron is added to a neutral gaseous atom called?

  Electron affinity
• Arrange the following elements in order of increasing non-metallic character: Li, Be, C, O, F

  1️⃣ Li

  2️⃣ Be

  3️⃣ C

  4️⃣ O

  5️⃣ F
• The element with the least electronegativity among Li, C, B, and F is Lithium
• If an element belongs to period 3 and group II, how many shells and valence electrons does it have?

  3 shells and 2 valence electrons
• Elements in the modern periodic table are arranged in order of increasing atomic number.
• How many electrons are present in the valence shell of a halogen?

  7
• The element with the highest ionization potential is Helium