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1. elements are composed of indivisible particles-atoms. 2. atoms of the same element are alike in mass and size. 3. atoms of different elements are not alike – they have different masses and sizes. 4. compounds are union of two or more atoms of different elements. 5. compounds contain simple numerical ratios of atoms. 6. more than one compound can be formed of atoms of two elements. Dalton rules: Rutherford conclusions: 1. Atom has minuscule nucleus, 100 000 smaller than the atom, containing all positive charge. 2. Electrons are negatively charged an orbit around atom nucleus. Mass of p is 1840 x mass of e- (1.67 x 10 - 24 g). are formed when an atom gains or looses electrons. er of protons give the identity of the atom. opes differ in number of neutrons and masses. U 235 92 Mass # Atomic # Average atomic mass is the sum of masses of isotopes multiplied with its abundance. It is assumed that the masses of p and n are equal, and electron masses are ignored. e mass of Cu is: (62.9298 x 0.6909) + ((64.9278 x 0.3091) = 63.55 Symbol Z mass# #p #n #e charge Br - 35 80 35 45 36 -1 S 16 34 16 16 18 -2 Z = #p. Mass# = #p + #n. charge = #p -

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Page 1: Dalton rules:

1. elements are composed of indivisible particles-atoms. 2. atoms of the same element are alike in mass and size. 3. atoms of different elements are not alike – they have different masses and sizes. 4. compounds are union of two or more atoms of different elements. 5. compounds contain simple numerical ratios of atoms.6. more than one compound can be formed of atoms of two elements.

Dalton rules:

Rutherford conclusions:1. Atom has minuscule nucleus, 100 000 smaller than the atom, containing all positive charge.

2. Electrons are negatively charged and orbit around atom nucleus.

Mass of p is 1840 x mass of e- (1.67 x 10-24 g).Ions are formed when an atom gains or looses electrons.

Number of protons give the identity of the atom.Isotopes differ in number of neutrons and masses. U235

92Mass #Atomic #

Average atomic mass is the sum of masses of isotopes multiplied with its abundance. It is assumed that the masses of p and n are equal, and electron masses are ignored.

Average mass of Cu is: (62.9298 x 0.6909) + ((64.9278 x 0.3091) = 63.55

Element Symbol Z mass# #p #n #e chargeBromine Br- 35 80 35 45 36 -1Sulfur S 16 34 16 16 18 -2

Z = #p. Mass# = #p + #n. charge = #p - #e.

Page 2: Dalton rules:

Metal and nonmetal usually make an ionic compound. Nonmetals create covalent bonding. Metals create cations (group IA: 1+, group 2A: 2+), nonmetals produce anions (group VIA: 2-, group VIIA: 1-) as all elements tend to create electron configuration of their closest noble gas.

Formula follows electronegativities of the elements.Binary, ionic compound: metal name unchanged, non-metal changes the ending to ide: Sodium chloride, NaCl.Transition metals contain charge in Roman numerals, Copper (II) oxide, CuO.Binary covalent compound: must give prefix how many atoms of each kind is in. N2O5: Dinitrogen pentoxide.

Polyatomic ions: ammonium NH4+, carbonate, CO3

2-, sulfate SO4

2-, nitrate, NO3-, phosphate, PO4

3-. The last three -ate anions have a similar –ite ion: same charge, one less oxygen atom in the formula.A compound must be neutral, so the sum of positive charges in an ionic compound must compensate the sum of negative charges. In Mg3(PO4)2. each Mg is 2+ charged, so the sum of positive charges is +6. Each (PO4) ion is 3-, thus the sum of negative charges is 6-.

Acids: If the acid contains no oxygen, make the name by prefix Hydro-, and suffix -ic acid. Hydrochloric acid, HCl. Oxyacids: If the anion ends with –ate, the acid ends with –ic. If the anion ends with –ite, the acid ends with -ous. Nitrate – nitric acid. Sulfite – sulfurous acid.

Cation Anions SO4

2- Cl- O2-

K+ K2SO4 KCl K2OH+ H2SO4 HCl H2O Zn2+ ZnSO4 ZnCl2 ZnOAl3+ Al2(SO4)3 AlCl3 Al2O3

Page 3: Dalton rules:

Al + Fe2O3 Fe + Al2O3 2 2

(s) (s) (s) (s)Formulas (substances), coefficients and symbols (+, ) make the core of a chemical equation. Physical state in parenthesis, conditions placed around

N2 + H2 NH3

Step 2: Start balancing metal first. Continue with nonmetals other than O or H.2

N: H:

22

N: H:

13

26

3

6Step 3: Balance O or H. if there is either O2 or H2 on the left side, balance it last.

Step1: Count atoms on each side.Balancing

Single-displacement reactions 2 Al(s) + Fe2O3(s) Al2O3(s) + 2 Fe(l)

Double-displacement reactions PCl3(l) + 3 AgF(s) PF3(g) + 3 AgCl(s)

Decomposition reaction 2 HgO(s) 2 Hg(l) + O2(g)Heat

Combination reaction H2(g) + I2(g) 2 HI(g)

Single displacement reactions require that the free element is more reactive than the one in the compound. Element reactivity is found in metal activity series and halogen activity series. Double displacement reactions require that either formation of water (accompanied by heat), gas or precipitate occurs.

CH4 + 2O2 → CO2 + 2H2O + 890 kJ

Energy of activation required to start a reaction. Heat is either absorbed (endothermic) or released (exothermic reaction).

Heat can be placed in the equation.

Page 4: Dalton rules:

s: 2 e- p: 6 e-

d: 10 e- f: 14 e-

1234

Period

1s2

4s2 4p6 4d10 4f14

3s2 3p6 3d10 2s2 2p6

Shells = periods (n= 1, 2, 3, …)Subshells = s, p, d, fOrbitals = electron pathways; each holds up to two electrons.

s p d f

SFe

S: 1s2 2s2 2p6 3s2 3p4 = [Ne] 3s2 3p4

Fe: 1s2 2s2 2p6 3s2 3p4 4s2 3d6 = [Ar] 4s2 3d6

Filling of the subshells: follow the periodic table3d is filled in 4th period 4f is filled in 6th period

1 2 3 4Orbital diagram

Electron configuration