Flashcards in Chapter 1-2 Deck (67):
Define chemical change/chemical reaction.
A change in which one or more new substances with different properties are formed as evidenced by changes in colour, energy, odour, or state; the study of chemicals and their reactions, associated technologies, and environmental effects.
A direct form of knowledge obtained by means of one of the five human senses and can be classified as qualitative or quantitative observation.
Define qualitative observation.
An observation that describes qualities of matter or changes in matter. (e.g. odour, colour, and physical state); observation with no numerical value.
Define quantitative observation.
An observation that involves one or more measurements of some property; observations with numerical value.
An indirect form of knowledge that builds upon a concept or an experience to further describe or explain an observation (included in the analysis).
Define empirical knowledge.
Knowledge gained through observation (observable knowledge). Observations are always empirical.
Define theoretical knowledge.
Knowledge that explains and describes scientific observations in terms of non-observables.
Define empirical descriptions.
Communicates a single item of empirical knowledge, that is, an observation.
Define empirical hypotheses.
Preliminary generalizations that require further testing.
Define empirical definitions.
Statements that define an object or a process in terms of observable properties.
Statements that summarize a limited number of empirical results. They are usually broader in scope than empirical definitions and often deal with a minor or sub-concept.
Define scientific laws.
Statements of major concepts based on a large body of empirical knowledge. Laws are more important and summarize more empirical knowledge than generalizations.
Anything that has mass and occupies space; may be a pure substance or a mixture.
Define pure substances.
Matter whose composition is constant and uniform; composed of only one kind of chemical and cannot be separated by physical methods.
Matter whose composition includes two or more substances and may or may not be uniform throughout the sample. (i.e. homogenous or heterogenous)
Define heterogeneous mixture.
A mixture that is non-uniform, and may consist of more than one phase. Heterogeneous mixtures can be separated by physical means (i.e. filtration, distillation, chromatography, mechanically extracting one component from the mixture, allowing one component to separate and settle, or use a magnet to separate certain metals.)
Define chemical decomposition.
Separating a compound into its elements.
A pure substance that cannot be broken down into simpler chemical substances by physical or chemical means; consists of only one atom.
A general term that includes atoms, ions, and molecules.
The smallest entity of an element that is still characteristics of that element.
A pure substance that can be separated into its elements by heat or electricity; a substance containing atoms/ions of more than one element in a definite fixed proportion. Compounds can only be separated by means of a chemical change involving heat or electricity.
Define chemical formula.
A series of symbols representing the atoms/ions and their proportions present in a pure substance.
What is the periodic table of elements and who created it?
The periodic table of elements communicates the periodic law (chemical and physical properties of elements that repeat themselves in regular intervals, when they are arranged in order of increasing atomic number.) The table organizes the elements in groups and periods as metals and non-metals.
It was created by Dmitri Mendeleev, a Russian chemist, in 1869.
What is a family/group in the periodic table of elements?
Family/groups have similar chemical properties and includes the elements in a vertical column in the main part of the table.
What is a period in the periodic table of elements?
A period is the horizontal row of elements whose properties gradually change from metallic to non-metallic from left to right along the row.
Location of metals, non-metals, and semi-metals in the periodic table of elements.
Metals on the left of the staircase line.
Non-metals are on the right.
Semi-metals (metalloids) are a class of elements distributed along the staircase line.
What is SATP?
Standard ambient temperature and pressure. A defined set of standard conditions for the description of materials.
A temperature of 25*C and a pressure of 100kPa.
What are metals?
Element that is shiny, bendable, good conductors of heat and electricity, and solids at SATP (except mercury).
What are nonmetals?
Not shiny, not bendable, generally not good conductors of heat and electricity at their solid form. At SATP, most nonmetals are gasses and a few are solids. Solid nonmetals are brittle and lack the luster of metals. Most nonmetals exist in compounds rather than in element form.
What is the rule for any element after uranium?
Ends in -ium.
What are alkali metals?
(Group 1 elements) Soft, silver-colored metals that react violently with water to form basic solutions. The most reactive alkali metals are cesium and francium.
What are alkaline earth metals?
(Group 2 elements which don't include beryllium ad magnesium) Light, reactive metals that form oxide coatings when exposed to air.
What are halogens?
(Group 17) Extremely reactive, with fluorine being the most reactive.
What are noble gasses?
(Group 18) Special gasses because of their extremely low chemical reactivity. They are all assumed to be monatomic.
What are transition elements?
(Group 3 to 11) Elements exhibit a wide range of chemical and physical properties.
What are main group elements?
(Group 1,2 and 12 to 18) Best follow the periodic law.
What are rare earth elements?
(Last 2 rows of the table that have common names) Includes lanthanoids, yttrium, and scandium.
What are lanthanoids?
Elements with atomic numbers 58-71
What are actinoids?
Elements with atomic numbers 90 to 103.
What are transuranic elements?
Synthetic (not naturally occurring) elements that have atomic numbers of 93 or greater. (Beyond uranium.)
Define theoretical descriptions.
Specific descriptive statements based on theories or models. (i.e. a molecule of water is composed of two hydrogen atoms and one oxygen atom)
Define theoretical hypotheses.
Ideas that are untested or extremely tentative. (i.e. Protons are composed of quarks that may themselves be composed of smaller particles.)
Define theoretical definitions.
General statements that characterize the nature of a substance or a process in terms of a non-observable idea. (i.e. a solid is theoretically defined as "a closely packed arrangement of atoms, each atom vibrating about a fixed location in the substance.")
A comprehensive set of ideas based on general principles that explain a large number of observations. Theories are dynamic and continually undergo refinement and change.
Explain Dalton's 1805 atomic theory.
- Law of definite composition, elements combine in a characteristic mass ratio
- Law of multiple proportions, there may be more than one mass ratio
- Law of conservation of mass, total mass remains constant as atoms are neither created or destroyed in a chemical reaction
Explain Thomson's 1897 atomic model.
Matter is composed of atoms that contain electrons (negatively charged particles) embedded in a positively charged material. The kind of element is characterized by the number of electrons in the atom.
Explain Rutherford's 1911 atomic theory and his experiment.
Experiment: Tested Thomson's theory and hypothesized that alpha particles should be deflected a little, if at all and the test showed that alpha particles were deflected at large angles and even backward.
Theory: An atom is composed of a very tiny nucleus which contains positive charges and most of the mass of the atom. Very small negative electrons occupy most of the volume of the atom.
Explain Bohr's 1913 atomic theory.
- Created a theory that could explain the periodic law.
- Periods in the periodic table result from the filling of electron energy levels in the atom.
- Last digit of the group number in the periodic table provides the number of electrons in the valence energy level.
An entity with a net positive or negative electrical charge due to the loss or gain of one or more electrons.
Define monatomic ion. What are the special ions?
A positively or negatively charged particle formed from a single atom by the loss or gain of electrons; also known as a simple ion.
- Transition metals
- Baron, carbon, and silicon (rarely form atoms)
- hydrogen (no negative ion)
Positively charged ions. Monatomic cations are formed from the metallic and semi-metal elements when they lose electrons in an electron transfer reaction.
Negatively charged ions. Monatomic anions come from the nonmetallic and semi-metal elements. Name for monatomic anions uses the stem of the English name or the element with the suffix "-ide" and the word "ion".
Predictions may be:
Verified or falsified.
Unacceptable theory strategies:
Restricted, revised, and/or replaced.
Define ionic compound.
A pure substance formed from a metal and non-metal; a crystalline solid at SATP with a relatively high melting point and a conductor of electricity in aqueous or molten states; a compound containing positive and negative ions.
Define aqueous solution.
A homogeneous mixture of one or more solutes dissolved in water.
Naming binary (two-element) compounds.
- Write chemical symbol, charge for the two ions and predict the simplest whole number ratio of ions to obtain a net charge of 0. *Switch charges*
Naming multi-valent metals.
(Most transition metals and some main group metals can form more than one kind of ion. i.e. Fe3+ or Fe2+)
- Balance the charges so the net charge is 0 *switch charges*
- Name of multi-valent metal includes the iron charge which is given in roman numerals.
Naming compounds with polyatomic ions.
- Same for naming binary compounds. Parentheses are used in the formula to indicate the presence of more than one polyatomic ion. Don't use parentheses when there is only one polyatomic ion or with simple ions.
Define molecular compounds.
Non-metal and non-metal combinations with a low melting point and is nonconducting of heat or electricity at any state.
An entity consisting of a group of nonmetal atoms held together by covalent bonds.
Define molecular formula.
A group of chemical symbols indicating the type and number of nonmetal atoms in a single molecule.
What do nonmetals frequently form?
Diatomic molecules (molecules containing two atoms).
When should you use the IUPAC Greek numerical prefixes? What is the special case for hydrogen?
For the names of molecular compounds formed from two different nonmetal elements. Hydrogen compounds don't use the prefix system.
Compound that neutralizes bases and turns blue litmus paper red. Hydrogen also appears first in the formula. (Unless it's a part of organic acids of -COOH acids.) It is assumed that acids are ionic compounds.
Classical names for acids are based on anion names.
- If the anion ends in "-ide", the corresponding acid is named as a "hydro---ic acid". (i.e. H2S(aq) is hydrosulfuric acid.)
- If the anion name ends in "-ate", the acid is named as a "-ic" acid. (i.e. HNO3(aq) is nitric acid)
- If the anion name ends in "-ite", the aci is named as a "-ous" acid. (i.e. H2SO3(aq) is sulfurous acid)