Compounds

• Compound- A collection of molecules
• Molecule- is created when two or more atoms link up
• The molecular mass is the sum of the masses of all the atoms in the molecule.
• Many atoms are more stable when they have a net charge: they are more stable as ions. When a cation gets close to an anion, they link up because of their different net charges — positive charges attract negative and vice versa.
• Ionic compounds are (usually) formed when a metal reacts with a nonmetal (or a polyatomic ion)
• Molecular compounds are electrically neutral.
• Covalent compounds are formed when two nonmetals react with each other.

  • Polar covalent bonds result when electrons are unequally shared between atoms

  • Nonpolar covalent bonds result when electrons are more equally shared between atoms.

  *The unequal sharing of electrons is due to the differences in the electronegativities of the two atoms

  sharing the electrons.
• Electronegativity is a chemical property that describes the tendency of an atom or a functional group to attract electrons toward itself.
• fluorine is the most electronegative
• francium is the least electronegative
• molecular compound- neutral charge
• covalent compound- polar or non polar (share electron) POLAR- ONE ELEMENT IS SLIGHTLY MORE ELECTRONEGATIVE NON POLAR- ALMOST THE SAME ELECTRONEGATIVITIES EXAMPLE: water (same non metals)
• ionic compound- give (always polar) metal to non-pmetal
• the electrons in a non polar covalent bond is- shared equally
• what is the charge on the ions frmed by the alkaline earth metals- +2
• What is the most correct name for the ionic compound formed by Fe²⁺ and Cl⁻?

  iron (II) chloride
• The outermost energy level of an electron is called its... -valence energy level
• On the periodic table, the periods are...

  • horizontal rows
• Metallic atoms tend to __________ electrons, forming cations.- give up
• The electron-dot structure of carbon has how many dots?

  -4
• What type of compound is formed when metal and non-metal elements combine? -Ionic Compound
• How many electrons are gained/lost by magnesium and what is the charge on the ion that it forms? -loses 2 electrons to form a magnesium ion with a 2+ charge
• What type of compound typically has a low solubility in water?

  -Molecular Compound
• What type of compound is composed of positively and negatively charged ions?

  -Ionic Compound
• What is the electronegativity difference between the elements in an ionic compound? -Greater than 2.0
• What is the main bonding type in a molecular compound? -Covalent Bond
• What type of bonds are formed in N₂O₄ and what is the name of this compound?

  -covalent, dinitrogen tetroxide
• The bond between sulfur (electronegativity value 2.5) and chlorine (electronegativity value 3.0) would be: -polar
• A _____________ bond is formed when two atoms share two pairs of electrons

  -double
• 17. Ionic compounds may contain polyatomic ions. For example, the formula of magnesium nitrate is:

  • Mg(NO₃)₂
• What is the formula of phosphorus trichloride? -PCl₃
• NON POLAR= <0.4