Chapter 3, Physical state of matter

Chemical formula

expresses the number of atoms of each element in a compound. For example, the molecule of water (H2O) contains two atoms of hydrogen and one atome of oxygen.

Solid matter has

fixed shape and fixed volume. The particles are tightly packed, held in rigid positions and cannot be compressed together.

Chemical symbol

Abbreviated name of each element

Changes of physical state:

As temperature increases, a solid melts to a liquid, and then liquid vaporizes to a gas. Conversely, as temperature decreases, a gas CONDENSES to a liquid, and the liquid then freezes to a solid.

List 3 most abundant elements on Earth:

Oxygen, silicon, and aluminum

Energy and chemical change:

The total energy before a reaction is the same as the total energy after reaction. However, some chemical changes release energy, whereas other absorb energy.

Deposition

a direct change of state from a gas to a solid. Example: ice in the freezer from warm air without a trace of liquid water.

Sublimination

a direct change of state from solid to a gas. Example: dry ice.

Matter

a substance that has mass and occupies volume

Molecule

a unit of matter composed of two or more nonmetal atoms.

Physical states of matter table:

a. Solid: shape-fixed, volume - fixed, compressibility - negligible. b. Liquid: shape - variable, volume - fixed, compressibility - negligible. c. Gas: shape- variable, volume - variable, compressibility - significant.

Physical state of metals:

all the metals are solid at normal temperature (25 degrees Celsius) except mercury (Hg).

Periodic table

arranged chart of the elements. Metals are placed on the left side, and nonmetals are placed on the right side, semi-metals between them. Hydrogen is an exception, has unusual properties, has been placed by itself.

Gaseous state

as the temperature increases, particles gain more energy and acquire enough energy to vaporize from liquid to gas.

Every substance can exist as solid, liquid, or gas

by changing temperature

Law of definite composition

compounds always contain the same elements in a constant proportion. Example: table salt is always compound of sodium and chlorine, no matter if it 's tiny crystal or a mount of salt.

Law of conservation of energy

energy can not be created nor destroyed, but it can be converted from one form to another. Example of physical change and energy: 1 gram of water observe 540 cal of hear during converting it to steam. Also, 540 cal of heat released when 1 gram of steam condenses into water.

Liquid matter:

has a variable shape, but a fixed volume. The particles are loosely packed, free to move around, compress only slightly.

Compound

has predictable properties, but can be broken down into elements by an ordinary chemical reaction. Table sugar is an example of compound, that can be broken down carbon, hydrogen, and oxygen.

6 forms of energy:

heat light chemical electrical mechanical nuclear Each of them can be converted from one form to another. For example: steam drives a turbine- heat energy is converted to mechanical energy.

Kinetic energy and temperature

if the t increases, the the motion of the particles increases and KE increases. If the t decreases, the motion of the particles and KE decreases.

Atom

invisible, spherical particles (Dalton proposed).

Potential energy (PE)

is STORED ENERGY that matter posses as a result of its position or composition.

Alloy

is a homogeneous mixture of two or more metals. The properties from different samples can vary. For example, 10K gold is a harder alloy and is more scratch resistant than 18K gold.

Element

is a substance that cannot be broken down further by a chemical reaction. For example, salt cannot be broken down any further.

A metal

is an element that typically is solid, has a bright metallic luster, a high density, a high melting point, and is a good conductor of heat and electricity, also reacts with non metals. A metal can be hammered into a thin sheet of foil (malleable) and can be drawn into a fine wire (ductile). Examples; aluminum, copper, silver.

A nonmetal

is an element that usually has a low density, a low melting point, crush to a powder (not malleable or ductile) and is a poor conductor of heat and electricity. Many nonmetals occur in the solid state and have a dull appearance. Also 11 nonmetals occur in gaseous state. React with metals and nonmetals.

A substance

is matter that has definite composition and constant properties. A substance is either a compound or an element.

Kinetic energy (KE)

is the energy matter has as a result of its MOTION

Oxygen

is the most abundant element on Earth (21 % of our atmosphere). It is found combined together with hydrogen in water and silicon in sand and rocks.

A sample of matter is heterogeneous if

it's properties are indefinite and vary. Heterogeneous mixture can be separated into pure substances by physical methods. Example: panning gold to separate from sand and rocks.

Chemical property

its chemical reaction with other substanses

Law of conservation of mass

matter was neither created neither destroyed during a chemical reaction. Example: 1 gram of hydrogen + 8 grams of oxygen = 9 grams of water.

Homogeneous:

properties are definite and constant.

Physical property

refers to characteristics of pure substances that we can observe without changing the composition of the substance: appearance, boiling and melting point, density, heat and electricity conductivity, solubility, physical state under normal conditions.

Physical state of nonmetals:

show great diversity at normal temperature and pressure. 5 are solid (carbon - C, phosphorus - P, sulfur - S, selenium - Se, and iodine - I). 1 is liquid (bromine - Br). 11 are gases (hydrogen - H, nitrogen - N, oxygen - O, fluorine - F, chlorine - Cl, helium - He, neon - Ne, argon - Ar, krypton - Kr, xenon - Xe, and radon - Rn).

Three physical states of matter:

solid, liquid and gas.

Physical change

the chemical composition of the sample doesn't change. In other words the formula of each substance remains constant. For example: melt ice to water, heat alcohol to vapor, recycle aluminum cans into aluminum foil.

Atomic number

the number that identifies a particular element in the periodic table

When the substance from SOLID state is HEATED

the temperature increases and the particles begin to randomly vibrate in fixed position. As a solid acquires more heat energy, particles vibrate so intensely that the force of attraction is overcome and particles break free from each other. This is a description of a LIQUID state.

In gaseous state:

tiny particles of matter are widely spaced apart, uniformly distributed through it container. If the volume increases, the gas expands and the particles move farther away from each other. if decreases, gas compresses, particles move closer.

Suffix commonly attached to the name of element:

-ium

Chemical change

there is a chemical reaction. The composition of a sample changes, we observe the new set of properties. Color change, odor, bubbles from the release of gas, light or heat from the release of energy.

Physical state of semimetals

they are solid at normal temperature and pressure.

Semimetals

( or metalloid) is an element that typically has properties midway between those of metals and nonmetals. Example- silicon.