49 terms

Chemistry Terms...

Chem 1315
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Pure substance
Matter that always has exactly the same composition. A pure substance is always an element or compound. A pure substance is matter that has distinct properties and a composition that does not change from sample to sample. ( water and sodium chloride are pure substances)
Element
Any substance that cannot be broken down into simpler substances. Composed of only one kind of atom. 118 known elements.
Compound
Substance formed by the chemical combination of two or more elements in definite proportions. (water is a compound formed of hydrogen and oxygen)
Mixture
Material composed of two or more elements or compounds that are physically mixed together but not chemically combined. Each retains its chemical identity. The composition of a mixture can vary. (a cup of coffee can have a little sugar or a lot)
How to convert from °C ↔ °K
°K= °C + 273.15
°C= °K − 273.15
Composition
The kinds of atoms matter contains (element, compound or mixture)
What does structure mean?
The arrangement of atoms in matter
What are the 3 states of matter?
Solid, liquid, gas
The law of constant (or definite) proportions:
Elemental composition of a compound is always the same. Stated by Proust in 1800.
Heterogeneous mixture:
Vary in texture and appearance in a sample.
Homogeneous mixture:
uniform throughout. They are also called solutions.
Physical properties:
Can be observed without changing the identity and composition of the substance. (color, odor, density, melting point, boiling point, hardness...)
Chemical properties:
Describes the way a substance may change or react to form other substances. (flammability, the ability to burn in the presence of oxygen)
Intensive properties:
Do not depend on the amount of the sample being examined. Useful for identifying substances. (temperature and melting point)
Extensive properties:
Depend on the amount of the sample being examined. (mass and volume)
Physical change:
A substance changes its physical appearance, but not its composition. It is the same substance before and after the change. (evaporation of water)
What is a chemical change (or chemical reaction)?
A substance is transformed into a chemically different substance. When hydrogen burns in air, because it combines with oxygen to form water.
Density equals_____?
mass divided by volume
The law of conservation of mass:
Mass is neither created nor destroyed during ordinary chemical reactions or physical changes.
Law of multiple proportions:
When two elements combine to form two or more compounds, the mass of one element that combines with a given mass of the other is in the ratio of small whole numbers.
Particles with the same charge ______ each other.
repel
Particles with opposite charges ______ each other.
attract
Every atom has an equal number of ______and ________.
protons and neutrons, so atoms have no net electrical charge.
atomic number:
Is equal to the number of protons in an atom's nucleus.
Mass number:
The number of protons and neutrons.
What are isotopes?
Atoms with the same atomic numbers but different mass numbers(same number of protons but different numbers of neutrons)
atomic weight:
Total weight of an atom. Equal to the number of protons and neutrons with little extra added by the electrons.
The horizontal rows of the periodic table are called________.
Periods
The vertical rows of the periodic table are called________.
Groups
Diatomic molecule:
A molecule made up of two atoms.
Molecular compounds:
composed of molecules and almost always contain only NONMETALS
empirical formulas:
Simplest formulas. the composition of a compound in terms of the relative numbers and kinds of atoms in the simplest ratio.
(H₂O₂ would be HO)
ionic compound:
Composed of positive and negative ions that are combined so that the numbers of positive and negative charges are equal. (usually a metal with a nonmetal)
Cations formed from metal atoms have the same name as the _____.
Metal.
(Na⁺=Sodium ion.
Zn²⁺=Zinc ion. )
Cations formed from nonmetal atoms have names that end in _____.
-ium.
(NH₄⁺=ammonium ion.
H₃O =hydronium ion)
The names of monoatomic ions are formed by replacing the ending of the name of the element with _____.
-ide.
(H⁻ =Hydride ion.
O²⁻ =Oxide ion.
N³⁻ =Nitride ion)
A few polyatomic anions also have names ending in -ide. Examples?
OH⁻ =hydroxide ion.
CN⁻ =cyanide ion.
O₂²⁻ =Peroxide ion.
Polyatomic anions containing oxygen have names ending in either -ate(most common) or -ite(one O atom less) and are called _________.
oxyanions.
(NO₃⁻ =nitrate ion.
NO₂⁻ =nitrite ion.
SO₄²⁻ =sulfate ion.
SO₃²⁻ =sulfite ion.)
Prefixes are used when the series of oxyanions of an element extends to four members, like with halogens. The prefix per- means one more O atom than the one that ends in ______. Hypo- indicates one atom fewer than the oxyanion ending in _______.
-ate, -ite.
(ClO₄⁻ =perchlorate ion
ClO₃⁻ =chlorate ion
ClO₂⁻ =chlorite ion
ClO⁻ =hypochlorite ion)
Anions derived by adding H⁺ to an oxyanion are named by adding _____or _____ as a prefix.
hydrogen or dihydrogen.
(CO₃²⁻ =carbonate ion
HCO₃²⁻ =hydrogen carbonate ion
PO₄³⁻ =phosphate ion
H₂PO₄⁻ -dihydrogen phosphate)
Names of ionic compounds consist of the cation name followed by the anion name. Examples?
CaCl₂ =calcium chloride.
Al(NO₃)₃ =aluminum nitrate.
Cu(ClO₄)₂ =copper(II) perchlorate.
Definition of an acid?
A substance whose molecules yield H⁺ ions when dissolved in water. When you encounter a chemical formula it will be written with H as the first element as in HCl and H₂SO₄.
Acids containing anions whose names end in -ide are named by changing the ending to _____ and adding the prefix _____.
-ic, hydro-.
(Cl⁻ =chloride
HCl =hydrochloric acid
S²⁻ =sulfide
H₂S =hydrosulfuric acid)
Acids containing anions whose names end in -ate or -ite are named by changing -ate to _____, and -ite to _____. Keep the prefixes.
-ic, -ous.
(ClO₄⁻ =perchlorate
HClO₄ =perchloric acid
ClO₃⁻ =chlorate
HClO₃ =chloric acid
ClO₂⁻ =Chlorite
HClO₂ =chlorous acid
ClO⁻ =Hypochlorite
HClO =hypochlorous acid)
1. Name binary compounds from left to right.
2. If both elements are in the same group, the lower one goes first.
3. The name of the second element gets an -ide ending.
4. Use Greek prefixes.
Examples?
Examples:
Cl₂O =dichlorine monoxide
NF₃ =nitrogen triflouride
N₂O₄ =dinitrogen tetroxide
P₄S₁₀ =tetraphosphorus decasulfide
Compounds that only contain carbon and hydrogen are called _____.
Hydrocarbons
Alkanes
Hydrocarbons containing only single bonds.
isomers
Compounds with the same formula but different structure.
Which 7 acids start with an H?
HCl= hydrochloric acid
H₂SO₄=
HNO₃=
HF= hydroflouric acid
HCN= hydrocyanic acid
HI= hydroiodic acid
H₂S= hydrosulfuric acid