Ions

• What are ions?

  Charged particles from atoms losing or gaining electrons
• Why do atoms form ions?

  To achieve a full outer shell of electrons
• What forms positive ions?

  Metals losing electrons
• What forms negative ions?

  Non-metals gaining electrons
• How is the charge of an ion determined?

  By the number of electrons lost or gained
• If an atom loses 2 electrons, what is the charge of the ion?

  2+
• How many electrons does Fe2+ have if it has 26 protons?

  24 electrons
• How many electrons does F– have if it has 9 protons?

  10 electrons
• Which groups of elements are most likely to form ions?

  Groups 1, 2, 6, and 7
• What do Group 1 and 2 elements have in common?

  They are metals that lose electrons
• What do Group 6 and 7 elements do to form ions?

  They gain electrons to form negative ions
• How do you determine the formula of an ionic compound?

  By balancing the charges of the ions
• Why do elements in the same group form ions with the same charges?

  They have the same number of outer electrons
• What is the formula for calcium nitrate?

  Ca(NO3)2
• What is the overall charge of an ionic compound?

  Zero
• How does sodium chloride (NaCl) form?

  Na loses an electron, Cl gains it
• What happens to magnesium when it reacts with oxygen?

  It loses two electrons to form Mg²⁺
• How does magnesium chloride (MgCl₂) form?

  Mg loses two electrons, Cl gains one each
• How does sodium oxide (Na₂O) form?

  Two Na atoms lose electrons to O
• What is a covalent bond?

  A bond formed by sharing electron pairs
• What are examples of simple molecular substances?

  H₂, O₂, H₂O, NH₃, CH₄, CO₂
• Why do simple molecular substances have low melting and boiling points?

  Weak intermolecular forces are broken
• What happens to the strength of intermolecular forces as molecules get bigger?

  They increase, requiring more energy to break
• What is a dot and cross diagram used for?

  To show electron arrangement in atoms or ions
• What is a polymer?

  A molecule made of long carbon chains
• Why is oxygen (O₂) a gas at room temperature?

  Weak intermolecular forces allow easy separation
• Why doesn’t nitrogen (N₂) conduct electricity?

  It has no free electrons or ions
• Why don’t molecular compounds conduct electricity?

  They lack free electrons or ions
• How are polymers formed?

  By joining small molecules called monomers