Presentation on theme: "Review of Atomic Model. Elements are pure substances containing one type of atom – found on the Periodic Table. The atom is the smallest part that retains."— Presentation transcript:
Elements are pure substances containing one type of atom – found on the Periodic Table. The atom is the smallest part that retains all the properties of that element. protons (p + )neutrons (n o )electrons (e - ) Charge Mass Location +1.6 x 10 -19 C0-1.6 x 10 -19 C 1.67 x 10 -24 g 9.11 x 10 -28 g Nucleus Orbit clouds
Octet rule: atoms react to acquire a full outer shell: Give away an e - to another atom. Take an e - from another atom. Share an e - with another atom. Ionic bond Covalent bond An ION is an atom that has lost or gained an electron. H : neutral atom H + : positive cation H - : negative anion
+1 +2 -3-2+3 +4/-4 Remember: The number of the column is equal to the valence electron number. Know that and you figure out the number of electrons lost or gained – the ionic charge
Ionic NaCl A compound has different characteristic properties than the atoms which form it. Covalent HCl
Ionic Compounds Contain a METAL and a NON-METAL atom. Formed by TRANSFERING valence electrons to fill outer shell – octet rule. A formula unit is the smallest unit of an ionic compound. Metal + Non-metal = ionic bonding
Writing Rule 1: Write the symbol of the metallic element first. Be Cl Rule 2: Place the combining capacity of one element as a subscript of the other element. Beryllium combines with Chlorine +- 1 2
Rule 3: Leave subscripts with a value of 1 out. Be Cl 21 Two Naming rules: 1.Write the full name of the metal ion first. 2.Name the non-metal ion dropping the last part of the name and adding the suffix “ide”. berylliumchloride
Rule 4: Reduce the subscripts if possible. Mg S Magnesium combines with Sulfur Mg S +- 2 2 magnesiumsulphide
Transition metals can give away different numbers of electrons. To avoid confusion: Brackets are used to show how many electrons the Transition metal is giving away.
Iron (III) chloride Iron (II) chloride Fe Cl +- 1 2 FeCl 2 Fe Cl +- 1 3 FeCl 3
Write the name of the ionic compound: PbO + - 1 2 lead oxide(IV) +4-2 Remember: Always look at the anion to see if it has been reduced. If it has, so has the metal.
Polyatomic Ions (poly = many) Groups of covalently bonded atoms that act as ions in ionic bonding. Polyatomic ions function as one unit with one charge – lose or gain electrons. NEVER change the subscripts of polyatomic ions. Al(C 2 H 3 O 2 ) 3
Write the name of the ionic compound: Al(C 2 H 3 O 2 ) Al C 2 H 3 O 2 +- 1 3 aluminum acetate
nickel (II) nitrate MgSO 4 potassium permanganate Fe(OH) 3 calcium acetate Ag 2 CrO 4 lead (II) carbonate Sn(SO 4 ) 2 sodium hydrogen phosphate NH 4 NO 2 1.Ni(NO 3 ) 2 2.magnesium sulfate 3.KMnO 4 4.iron (III) hydroxide 5.Ca(C 2 H 3 O 2 ) 2 6.silver chromate 7.PbCO 3 8.tin (IV) sulfate 9.Na 2 HPO 4 10.ammonium nitrite
Covalent Compound Contain two or more NON-METAL atoms. Formed by SHARING valence electrons to fill outer shell – octet rule. A molecule is the smallest unit of a covalent compound. Non-metal + Non-metal = covalent bonding
Step 1: first non-metal is named with a prefix to show the number of atoms. We do not use “mono” for the first non-metal. nitrogen oxide N O Step 2: second non-metal is named with a prefix AND with the “ide” ending. di 24 tetra dinitrogen tetroxide Prefix Number of Atoms mono1 di2 tri3 tetra4 penta5 hexa6
Writing formulas Step 1: Write the symbol of each element. Step 2: Use a subscript to show the number of each type of atom given by the prefix. Do not reduce covalent formulas. phosphorus oxide P O di 2 5 penta Prefix Number of Atoms mono1 di2 tri3 tetra4 penta5 hexa6
Does it have a metal? NO (covalent) YES (ionic) Is it a transition? NO charges NO criss-cross Use prefixs Ends in “ide” Find charges Reverse Criss-cross Use Brackets Ends in “ide” Find charges Criss-cross Ends in “ide” MgCl 2 magnesium chloride CuCl 2 copper (II) chloride OCl 2 oxygen dichloride NO YES Polyatomic Find charges Reverse Criss-cross Don’t change ending Fe(NO 3 ) 2 iron (II) nitrate
Many reactions are similar Chemists have classified 5 types of reactions BIG PICTURE IDEA: If you know the reactants - you can guess the type of reaction AND predict the products
Synthesis A + B C DecompositionC A + B Single replacementA + BC B + AC Double replacement AC + BD AD + BC Carbon Combustion C x H y + O 2 CO 2 + H 2 O
Diatomic Elements: Elements that are most commonly found in a covalent bond with itself. I Have No Bright Or Clever Friends I 2 H 2 N 2 Br 2 O 2 Cl 2 F 2
Explain the difference between isotope and radioisotope Explain average atomic mass using isotopes and their relative abundance Additional KEY Terms Radioactive decayHalf-life
The atomic number (Z) is the number of protons in the nucleus of an atom - identifies an element. The atomic mass (A) is the number of protons plus the number of neutrons.
Isotopes: Atoms with the but a different number of neutrons. same number of protons Deuterium Atomic Mass = 2 Atomic Number = 1 Hydrogen Atomic Mass = 1 Atomic Number = 1 Atomic mass is actually an average of isotopes of an element based on relative abundance in nature
Mass spectrometer determines the mass of individual atoms or isotopes. Sends atoms through a magnetic field which bends their paths. The heavier the atom – the less it bends
Potassium isotopes: 1. 19 protons and 20 neutrons - mass number of 39 (potassium-39 39 K) 2. 19 protons and 21 neutrons - mass number of 40 (potassium-40 40 K) 3. 19 protons and 22 neutrons - mass number of 41 (potassium-41 41 K)
Magnesium exists as three isotopes in the world: 78.99% is 24 Mg (23.985 μ) 10.00% is 25 Mg (24.986 μ) 11.01% is 26 Mg (25.982 μ) (0.7899)(23.985 μ) = 18.95 μ (0.1000)(24.986 μ) = 2.499 μ (0.1101)(25.982 μ) = 2.861 μ = 24.31 μ + Calculate the average atomic mass of magnesium:
helium 5 He 6 He The nucleus of some isotopes are unstable and break apart over time - radioactivity.
Radioisotopes - unstable nuclei releasing energy and/or particles. Release of energy is called radioactive decay. Half-life - amount of time it takes for half the radioisotope to be converted into another particle. Atoms may be converted into another isotope or a completely different element
Many different types of decay exist: alpha decay, beta decay, gamma decay
CAN YOU / HAVE YOU? Explain the difference between isotope and radioisotope Explain average atomic mass using isotopes and their relative abundance Additional KEY Terms Radioactive decayHalf-life
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