CHEM1011 Lecture 2: Lecture 2

Stadent An Introduction to the Chemical Basis of Life Thiere ave ninety-two naturally occurring elements in the universe. An element is a substance that canniot he separated into simpler substances by purely chemical means The smallest indivisible unit of an element is the atom is composed of three fundamental particles, protons s and electrons Protons are positively charged particles and along with neutrons, which not have any electrical change and are therefore n neutron cutral. are found in the nucleus of the atom Electrons are negatively charged particles that occupy specific orbits around the nucleus t with cach to form discrete units called molecules The atoms of a molecule can te kind or different kinds; that is, they can be the same or different clements be the sa Molecules containing atoms of two or more known as compounds different elements in specific proportions are Objective: Review and practice chemical concepts introduced in your lecture Using your lecture notes, textbook and the periodic table provided 1. Worksheet: identify in one or two sentences the following concepts related to the periodic table: Family or Group · Period Mctal Transition Element Non-metal . Inert gases Valencoe Electronegativity

tion (A Principles of Chemistry I Midterm Lecture Examination(A) 14. A(n) is a pure substance that is composed of only one type of atom. a) ion b) homogencous mixture c) element d) chemical bond e) chemical compound 15. Which two of the following atoms are isotopes? 1 :Ce, in La·'[Ba , 1 [Ba a) w Ce and L b) Ce and Ba Ba e) sBa andBa 16. The reaction of elemental chlorine with potassium iodide yields elemental iodine a potassium chloride. Write a balanced chemical equation for this reaction. a) Cl2(g)+ KI(s) → I(s)+ KC12(s) b) C12(g) 2 KI(s) → 12(s) + 2 KCl(s) c) C12(g) + K12(s) → 12(s) + KC12(s) d) Cl(g) + KI(s) → I(s) + KCl(s) e) C12(g) + 2 Kal(s) → 12(s) + 2 KaCl(s) 17. A pure substance composed of two or more different elements is a) an ion. b) a homogeneous mixture. c) a chemical compound. d) a solid. e) an atom. 18. Which of the following statements is/are correct? 1) All ionic compounds that are soluble in water are electrolytes 2) All ionic compounds dissolve in water. 3) Molecular compounds are never soluble in water. a) I only b) 2 only c) 3 only d) 1 and 2 e) 2 and 3 Page 4 of