Chem unit 2 vocab

Kinetic molecular theory

-Particles of matter are always in motion

relative kinetic energy of particles in solid

very low

relative kinetic energy of particles in liquid

low

relative kinetic energy of particles in gas

high

Relative particle spacing in solid

small

relative particle spacing in liquid

medium

relative particle spacing in gas

large

shapes of particles in solid

Constant/doesn’t change

shape of particles in liquid

varies/takes on shape of container

shape of particles in gas

expands or contracts/takes up entire space of container

Physical properties

characteristics of matter that can be observed or measured without changing the identity of the matter

melting

solid → liquid

vaporization

liquid → gas (heats)

deposition

gas → solid

freezing

liquid → solid

condensation

gas → liquid (cools)

sublimation

solid → gas

Phase change heating curve

Energy during phase change 

→ kinetic energy remains constant

→ potential energy changes

chemical properties

are related to matter’s ability to undergo changes that transform one matter with a set of properties into another kind of matter with a different set of properties

→ chemical changes result in one or more kind of matter changing into a different kind of matter

law of definite composition

a given compound always contains the same, fixed ratio of elements and can be represented by a chemical formula

→ Water is always H2O

law of multiple proportions

elements can combine in different ratios to form different compounds

temperature

-A measure of the average kinetic energy (ke) of particles in a sample of matter

-Is directly proportional to KE

-Does NOT depend on the identity or mass of a substance

-Does NOT depend on the size or mass of a sample

-Not a form of energy and is measured in Celsius, Kelvin, or Fahrenheit

heat

-Thermal energy that flows between objects that are at diff. temperatures

-Transfers through molecular collisions from hotter objects to cooler objects until the two objects are at the same temp.

-Depends on the size of a sample

-Depends on the identity of a substance

-A form of energy that is measured in joules (J)

specific heat capacity

-The amount of heat needed to raise the temp. of 1g of any substance by by 1K or 1 C

-Matter w/a higher specific heat capacity requires more energy to heat

Heat capacity

A matter’s unique capacity to absorb heat

exothermic reaction

q < 0 indicates heat lost

endothermic reaction

q > 0 indicates heat gained

enthalpy

-🔺H can be calculated by using data collected from a chemical reaction that occurs inside a calorimeter

-heat energy released or absorbed by a chemical reaction is equal to the change in enthalpy

Calorimetry

the science of using a calorimeter to measure the change in heat of a physical process or a chemical reaction

conduction (Heat transfer)

energy is transferred by direct contact

radiation (heat transfer)

energy is transferred by electromagnetic radiation through space or air

convection (heat transfer)

energy is transferred by the movement of matter

Sign of a physical change

change in size

Sign of a physical change

change in shape

Sign of a physical change

change in state

Sign of a physical change

new substance is NOT formed

Sign of a chemical change

Change in physical and chemical properties

Sign of a chemical change

formation of a new substance

Sign of a chemical change

color change

Sign of a chemical change

production of heat/light

Sign of a chemical change

formation of gas

Sign of a chemical change

odor change

pure substance

-has a chemical formula

-can NOT be physically separated

mixture

-has NO chemical formula

-can be physically separated

elements

-are pure substances that are made up of only ONE kind of atom

-every symbol on the periodic table represents a pure substance in the form of an element

-an atom is the smallest unit of an element that maintains the properties of that element

compounds

-matter that is composed of atoms of two or more kinds of elements that are chemically bonded

-properties are different than their individual elements (Na + Cl2 = NaCl)

-molecules are the smallest unit of a compound that retains all the properties of that compound

molecules that are not compounds

hydrogen (H2), oxygen (O2), and nitrogen (N2) are examples of molecules that are not compounds because each is composed of atoms of only ONE KIND of element.

Homogenous mixtures

-the composition IS uniform

-different substances that are mixed together cannot be detected but can be physically separated

Homogenous mixtures (solutions)

-made up of very small particles that do not settle

-liquid solutions do not look cloudy

-particles do not scatter light (no Tyndall effect)

homogenous mixtures (alloys)

-solid solutions in which 2 or more metals are uniformly mixed

→ brass (zinc + copper)

→ sterling silver (silver + copper)

heterogenous mixtures

-composition is NOT uniform

-different substances that are mixed together can be detected and be physically separated

Heterogenous mixtures (colloids)

-particles are medium size

-particles do not settle (mayo, cheese, butter, whipped cream)

-particles scatter light (display Tyndall effect)

-separates over time

heterogenous mixtures (suspensions)

-do NOT have uniform composition

-particles are large

-particles settle (orange juice with pulp, muddy water)

7 molecules that are not compounds

hydrogen, nitrogen, oxygen, fluorine, chlorine, bromine, iodine