How Atoms Combine (7.3)
Atoms combine to become more ________. The most stable elements in the periodic table are the ___________________ because they have the maximum number of _____________ in their outermost orbits. (they have _____ valence electrons) Elements ________ to try and get a valence shell. There are 3 ways in which an atom that does not have a full valence shell can fill it: 1. it can __________ electrons, 2. it can __________ electrons, 3. it can __________ electrons. All 3 methods result in the formation of a chemical ___________. A chemical bond is the attraction between 2 _________. stable Noble gases electrons 8 react full gain Ionic bond lose share covalent bond bond atoms
IONIC COMPOUNDS (metals & non-metals)
IONIC BONDING metal non-metal oppositely charged Ionic bonds are formed between __________ elements and _____________ elements. Circle the compounds below that contain ionic bonds. KCl H2O O2 MgO Na2S NH3 Cl2 Ionic bonds are formed by the attraction of 2 ____________ charged ions (an ion is a _________ particle). metal non-metal oppositely charged
IONIC COMPOUNDS + - Na Cl Example 1: Sodium (Na) and Chlorine (Cl) 11 17
IONIC BONDING Example 1: Sodium (Na) and Chlorine (Cl) the sodium atom its outermost electron to chlorine so that both atoms get a full outer shell (and become ___________). Sodium has lost an electron and now has a _____________ charge, while chlorine has gained an electron and now has a _____________charge. ______________ charged atoms ___________, forming an _____________ bond. loses stable positive negative oppositely attract ionic
IONIC BONDING - + + - F Mg F Example 2: Magnesium (Mg) and Fluorine (F) - F 9 + + Mg 12 - F 9
IONIC BONDING Example 2: Magnesium (Mg) and Fluorine (F) Magnesium needs to lose electrons. Fluorine needs to gain electron. Magnesium can only lose two electrons if it reacts with fluorine atoms. The formula for this compound is ___________ 2 1 2 MgF2
Molecules & Covalent Bonding
Molecules & Covalent Bonding Covalent bonds are formed from ____________ elements. Unlike ionic bonds that are formed from ions that have ______ or ________ electrons, covalent bonds are formed from atoms that _______ electrons. The attraction of 2 atoms for the shared pair of electrons results in a __________ bond. Two or more atoms joined by covalent bonds form a __________. non-metal lost gained share covalent molecule
Molecules & Covalent Bonding Example #1: Hydrogen Molecule The hydrogen molecule consists of 2 hydrogen atoms. Each hydrogen atom has _____ valence electron. If each atom shares its electron with the other atom, then each atom has _____ electrons in their outer shell (1st shell). The shell is now full and the atoms (and molecule) are ______________. 1 2 stable
Molecules & Covalent Bonding Bohr-Rutherford diagrams: Electron Dot diagrams: H H H H H2 The formula for a hydrogen molecule is .
Molecules & Covalent Bonding Example #2: Hydrogen and Chlorine Hydrogen and chlorine each need more electron in order to have a full shell. They do this by one pair of . Electron Dot diagrams: H Cl H Cl The formula for the compound with hydrogen and chlorine is . 1 sharing electrons HCl
Molecules & Covalent Bonding Example #3: Hydrogen and Oxygen Hydrogen needs more electron in order to have a full outer shell. Oxygen needs ____ more electrons to have a full outer shell. Oxygen can get a full shell if it shares its 2 unpaired electrons with hydrogen atoms. This also gives each hydrogen atom a full outer shell. 1 2 2
Molecules & Covalent Bonding Electron Dot diagrams: H O O H H H The formula for the compound with hydrogen and oxygen is . This compound is known as ________. H2O water
Molecules & Covalent Bonding NOTE: When drawing electron dot diagrams for a molecule, use the stable octet rule. With the exception of hydrogen, each atom of the molecule should have 8 electrons (dots) surrounding it (including shared electrons).
dissolved in water - yes Ionic Compounds Molecular (Covalent) Type of Bonds ionic covalent Types of Elements involved metals & non-metals non-metals only State at 20C solid solids, liquids, gases Forces between Ions or Molecules very strong weak Melting & Boiling Points high relatively low Solubility in Water soluble many are not soluble Conducts Electricity? solid – no liquids – yes dissolved in water - yes no Examples NaCl (salt) CaO AgNO3 H2 H2O CCl4