Chem I notes (Rusty)

Chem I notes (Rusty) - Chapter 1 Chemistry is the study of...

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Chapter 1 Chemistry is the study of the properties of matter and the changes it undergoes. Elements and compounds are substances that take part in chemical transformations To characterize a substance, we need to know its physical properties, which can be observed without changing its identity, and chemical properties, which can be demonstrated only by chemical changes. Chemistry is a quantative science and requires measurements. The measured quantities usually have units associated with them. The units used in chemistry are based on the international system (SI) units. Scientific notation is used to express large ad small numbers, and each number in a measurement must indicate the meaningful digits, called significant figures. A simple and effective way to perform chemical calculations is dimensional analysis. In this procedure, an equation is set up in such a way that all the units cancel except the ones for the final answer. Chemistry: the study of matter and the changes it undergoes A branch of science concerned with the composition, characterization and transformation of matter Matter: anything that occupies space and has mass Substance: a form of matter that has a definite composition and distinct properties Pure Substance: has a fixed composition with identical characteristics and properties throughout (includes compounds or elements) Mixture: a combination of two or more substances in which the substances retain their distinct identities Homogeneous Mixture: composition of the mixture is the same throughout Heterogeneous Mixture: composition of the mixture is not the same throughout Solution (not necessarily a liquid): Homogeneous mixture consisting of: Solute: The substance to be dissolved The substance that goes through the phase change The lesser amount Solvent: The dissolving medium The substance that does not undergo a phase change The greater amount Gas: A gas naturally (at room temperature) Vapor: A solid or liquid naturally (at room temperature) Fluid: The ability to pour out or flow (liquids and gases) Element: a substance that cannot be separated into simpler substances by chemical means Groups ^ Periods > Compound: a substance composed of two or more different elements chemically united in fixed proportions Physical Properties : properties that can be observed without changing the identity of a substance Chemical Properties : properties that can be demonstrated only by chemical change Signs of chemical changes:
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1. Formation of a gas (bubbles) 2. Color change (though not necessarily chemical) 3. Formation of precipitate (insoluble solid that falls out of solution) 4. Change in temperature (not necessarily chemical) Qualitative : general observations Quantitative : observations expressed with numbers Intensive : those properties that can be used to identify a particular substance (boiling point, melting point, density, solubility) Extensive: not for identification, very with size of sample (mass, volume) Law : a concise verbal or mathematical statement of a relationship between phenomena
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Chem I notes (Rusty) - Chapter 1 Chemistry is the study of...

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