FA23 CHEM 111- Chapter 1- PART A edited.pdf

Chapter 1 Keys to the Study of Chemistry & The Components of Matter 1-2  Keys to the Study of Chemistry 1.1 Some Fundamental Definitions 1.2 Chemical Arts and the Origins of Modern Chemistry 1.3 The Scientific Approach: Developing a Mode...

Chapter 1 Keys to the Study of Chemistry & The Components of Matter 1-2  Keys to the Study of Chemistry 1.1 Some Fundamental Definitions 1.2 Chemical Arts and the Origins of Modern Chemistry 1.3 The Scientific Approach: Developing a Model 1.4 Measurement and Chemical Problem Solving 1.5 Uncertainty in Measurement: Significant Figures 1-1 Chemistry Chemistry is the study of matter, its properties, the changes that matter undergoes, and the energy associated with these changes. Definitions anything that has both mass and volume Matter – the “stuff” of the universe: books, planets, trees, professors, students the types and amounts of simpler substances Composition that make up a sample of matter Properties the characteristics that give each substance a unique identity 1-3  The States of Matter A solid has a fixed shape and volume. Solids may be hard or soft, rigid or flexible. A liquid has a varying shape that conforms to the shape of the container, but a fixed volume. A liquid has an upper surface. A gas has no fixed shape or volume and therefore does not have a surface. 1-4  Physical Properties Chemical Properties properties a substance shows by itself properties a substance shows as it without interacting with another substance interacts with, or transforms into, other substances – color, melting point, boiling point, density – flammability, corrosiveness 1-5 Temperature and Change of State A change of state is a physical change. – Physical form changes, composition does not. Changes in physical state are reversible – by changing the temperature. A chemical change cannot simply be reversed by a change in temperature. 1-6 Energy in Chemistry Energy is the ability to do work. Potential Energy Kinetic Energy Total Energy = is energy due to is energy due to Potential Energy + the position of an the movement Kinetic Energy object. of an object. Energy Changes Lower energy states are more stable and are favored over higher energy states. Energy is neither created nor destroyed – it is conserved – and can be converted from one form to another. 1-7 Potential energy is converted to kinetic energy. A gravitational system. The potential energy gained when a weight is lifted is converted to kinetic energy as the weight falls. A lower energy state is more stable. A system of two balls attached by a spring. The potential energy gained by a stretched spring is converted to kinetic energy when the moving balls are released. Energy is conserved when it is transformed. 1-8  Potential energy is converted to kinetic energy. A system of oppositely charged particles. The potential energy gained when the charges are separated is converted to kinetic energy as the attraction pulls these charges together. A system of fuel and exhaust. A fuel is higher in chemical potential energy than the exhaust. As the fuel burns, some of its potential energy is converted to the kinetic energy of the moving car. 1-9  Figure 1.6 The scientific approach to understanding nature. Natural phenomena and measured Observations events; can be stated as a natural law if universally consistent Hypothesis Tentative proposal that explains Hypothesis is observations revised if experimental results do not support it. Experiment Procedure to test hypothesis; measures one variable at a time Set of conceptual assumptions that Model (Theory) explains data from accumulated Model is altered if experiments; predicts related phenomena predicted events do not support it. Further Tests predictions based on Experiment model 1-10