1 Extensive properties of a pure substance depend on sample size whereas intensive properties are characteristic of that substance. Which of these properties are intensive? I) Color II) Mass III) Density A) I and II B) I and III C) II and III D) I, II and III
2 Atomic Theory • Several key observations lead to the theory of atoms • Law of the conservation of Mater : Mass is neither created or destroyed in chemical process • It is just moved around • Limits possibilities of chemical reactions • Leads directly to . . . • Law of multiple proportions : When two elements form a series of compounds, the ratio of the masses of each elements can always be reduced to a whole number
Atomic Theory • Nature only allows certain combinations of masses • Combination of atoms • Oxygen and hydrogen mostly react with the ratio : 8 ? ���𝑔�� 1 ? ℎ� �� �?�? • Can write Molecular formula of water as H 2 O: 2 mol hydrogen (mass 1g each) and one mol oxygen (16g) 16 𝑔 ���𝑔�� � 8 𝑔 ���𝑔�� � 3 2 𝑔 ℎ��𝑔�𝑔�� � � 1 𝑔 ℎ��𝑔�𝑔�� � =
What is an atom? • Atoms are made of protons(p + ) , electrons(e - ) and neutro • Millika ns (n 0 ) n's oil drop experiment ww w . y outube. c o m/ w a t c h?v= X MfYH and n 0 are densely spaced in the nu rford Gold foil experiment • http:// • The p + • Ruthe ag7Liw cleus • h t tp : // w w w . y outube. c o m/ w a t c h?v=X B qHk r af 8 iE 4
5 The amu • Atoms so small special unit used to describe their mass • amu → atomic mass unit • 1 amu = 1.6606x10 -24 g • Value set so carbon-12 atom has mass of exactly 12.0 amu
e - p + n 0 Hydrogen 1.0078 amu Hydrogen 2.0140 amu Hydrogen Ion 1.0072 amu Carbon 6p + 6n 0 12 amu Carbon 6p + 7n 0 13.0034 amu Carbon ion 6p + 6n 0 11.9994 amu 6
e - p + n 0 Hydroge n Hydroge n Hydrogen Ion Carbon 6p + 6n 0 Carbon 6p + 7n 0 Carbon ion 6p + 6n 0 11.9994 amu 1.0078 amu 2.0140 amu 1.0072 amu 12 amu 13.0034 amu How many protons are in How many neutrons are in How many electrons are in , , and , , and , , and ? 6, 6, and 6 ? 6, 7, and 6 ? 6, 6, and 7 7
e - p + n 0 Hydroge n Hydroge n Hydrogen Ion Carbon 6p + 6n 0 Carbon 6p + 7n 0 Carbon ion 6p + 6n 0 11.9994 amu 1.0078 amu 2.0140 amu 1.0072 amu 12 amu 13.0034 amu Using the answers to the previous three questions. and are isotopes and and are isotopes.
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