2The AtomAtom is the basic unit of an element, made up of even smaller particles called subatomic particles.There are three fundamental components (subatomic particles) that are important in chemistry: Electron, Proton and Neutron.The protons and neutrons of an atom are packed in an extremely small nucleus.Electrons are shown as ‘clouds’ around the nucleus.
3Nucleus The Structure of the Atom Electron (cloud) Figure above shows the location of the protons,Neutrons and electrons in an atom
4Subatomic Particlesmass p = mass n = 1840 x mass e-
5Atomic Number, Mass Number & Isotopes Atomic number (Z) = number of protons in nucleusMass number (A) = number of protons + number of neutrons= atomic number (Z) + number of neutronsIsotopes are atoms of the same element (X) with different numbers of neutrons in their nucleiMass NumberXAZElement SymbolAtomic Number
9Chemistry In Action Natural abundance of elements in Earth’s crust Natural abundance of elements in human body
10A diatomic molecule contains only two atoms Molecules & IonsA molecule is an aggregate of two or more atoms in a definite arrangement held together by chemical bondsH2H2ONH3CH4A diatomic molecule contains only two atomsH2, N2, O2, Br2, HCl, COA polyatomic molecule contains more than two atomsO3, H2O, NH3, CH4
11cation – ion with a positive charge An ion is an atom, or group of atoms, that has a net positive or negative charge.cation – ion with a positive chargeIf a neutral atom loses one or more electronsit becomes a cation.Na11 protons11 electronsNa+11 protons10 electronsanion – ion with a negative chargeIf a neutral atom gains one or more electronsit becomes an anion.Cl-17 protons18 electronsCl17 protons17 electrons
12A monatomic ion contains only one atom Na+, Cl-, Ca2+, O2-, Al3+, N3-A polyatomic ion contains more than one atomOH-, CN-, NH4+, NO3-
13How many protons and electrons are in Do You Understand Ions?How many protons and electrons are inAl2713?3+How many protons and electrons are inSe78342-?
15A molecular formula shows the exact number of atoms of each element in the smallest unit of a substanceAn empirical formula shows the simplestwhole-number ratio of the atoms in a substanceH2OmolecularempiricalC6H12O6O3N2H4
16The ionic compound NaCl ionic compounds consist of a combination of cations and an anionsthe formula is always the same as the empirical formulathe sum of the charges on the cation(s) and anion(s) in each formula unit must equal zeroThe ionic compound NaCl
17Formula of Ionic Compounds 2 x +3 = +63 x -2 = -6Al2O3Al3+O2-1 x +2 = +22 x -1 = -2CaBr2Ca2+Br-1 x +2 = +21 x -2 = -2Na2CO3Na+CO32-
19Naming Compound Ionic Compounds BaCl2 K2O Mg(OH)2 KNO3 often a metal + nonmetalanion (nonmetal), add “ide” to element nameBaCl2K2OMg(OH)2KNO3
20Transition metal ionic compounds indicate charge on metal with Roman numeralsFeCl22 Cl- -2 so Fe is +2FeCl33 Cl- -3 so Fe is +3Cr2S33 S-2 -6 so Cr is +3 (6/2)
21Molecular compounds nonmetals or nonmetals + metalloids common names H2O, NH3, CH4, C60element further left in periodic table is 1stNF3 , NO2element closest to bottom of group is 1stSO2if more than one compound can be formed from the same elements, use prefixes to indicate number of each kind of atomlast element ends in ide
23Acid & BasesAn acid can be defined as a substance that yieldshydrogen ions (H+) when dissolved in water.HClPure substance, hydrogen chlorideDissolved in water (H+ Cl-), hydrochloric acidAn oxoacid is an acid that contains hydrogen, oxygen, and another element.HNO3nitric acidH2CO3carbonic acidH2SO4sulfuric acid