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)
Any substance that cannot be broken down into simpler substances. Composed of only one kind of atom. 118 known elements.
Substance formed by the chemical combination of two or more elements in definite proportions. (water is a compound formed of hydrogen and oxygen)
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
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.
Vary in texture and appearance in a sample.
uniform throughout. They are also called solutions.
Can be observed without changing the identity and composition of the substance. (color, odor, density, melting point, boiling point, hardness...)
Describes the way a substance may change or react to form other substances. (flammability, the ability to burn in the presence of oxygen)
Do not depend on the amount of the sample being examined. Useful for identifying substances. (temperature and melting point)
Depend on the amount of the sample being examined. (mass and volume)
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.
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.
Particles with opposite charges ______ each other.
Every atom has an equal number of ______and ________.
protons and neutrons, so atoms have no net electrical charge.
Is equal to the number of protons in an atom's nucleus.
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)
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________.
The vertical rows of the periodic table are called________.
A molecule made up of two atoms.
composed of molecules and almost always contain only NONMETALS
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)
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 _____.
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?
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?