Chemistry Quiz #3 (Atomic structure, isotopes, average atomic mass)

Matter

Anything that has mass and takes up space

Pure substance

matter with a fixed composition, and constant properties. an element like gold or compound (H20)

Element

A pure substance that cannot be broken down into simpler substances by chemical means. Defined by number of protons

What does Z stand for?

The number of protons

Compound

A pure substance consisting of two or more elements chemically bonded together at a fixed ratio 

Example of an element

Oxygen (O)

Example of compound

Salt (NaCl)

Mixture

two or more substances that are physically combined, but not chemically bonded

example of a mixture

saltwater

homogeneous mixture

also called a solution, visually appears as one substance 

heterogenous mixture

a mixture that is not uniform. the componenets are visually distinguishable 

example of heterogenous mixture

chocolate chip cookie

Proton (p+)

a positively charged particle found in the nucleus

What does the proton determine

the elements identity

Neutron (N^0)

A neutrally charged particle found in the nucleus. contributes to the mass but not the charge 

Electrons (e-)

A negatviely charged particle that orbits the nucleus, has a negligible mass 

Atomic number (Z)

the number of protons in the nucleus of an ato.

Example of atomic number

Oxygen (O) has an atomic number (Z) of 8

Mass number (A)

The total number of protons and neutrons added

Example of mass number

Carbon - 14 has a mass number of 14

Isotope

atoms of the same element (same protons, but w/ different number of neutrons) different mass number 

Ion

a atom that has gained or lost one or more electrons, net electrical charge 

Cation

a ion with a positive charge: losing electrons

Anion

An ion with a negative charge, more electrons that protons.

Average atomic mass

the weighted average of the masses of all the naturally occuring isotopes of an element.

Average atomic mass calculations

multiply by their percentages by the masses and then add them all up 

atom

the basic unit of a chemical element

molecule

a group of atoms bonded together. one or more atoms

Protons

atomic number (Z) on the periodic table

Neutrons

Mass number (A) - atomic number (Z)

Electrons (e-)

p+ - (charge)