Unit 2 Building Blocks of Matter: Particles DOVES

atom

Smallest particle of an element

electron

A subatomic particle that has a negative charge

proton

A subatomic particle that has a positive charge and that is found in the nucleus of an atom

neutron

A subatomic particle that has no charge and that is found in the nucleus of an atom

nucleus

Center of an atom

cathode ray

a stream of electrons produced at the negative electrode of a tube containing a gas at low pressure

Solid Sphere Model

Dalton- an atom is little more than a singular, solid particle without other components.

Plum Pudding Model

J.J Thomsons model of an atom, in which he thought electrons were randomly distributed within a positively charged cloud

Nuclear Model

Rutherford's model of the atom with a nucleus containing protons and neutrons and with electrons in the space outside the nucleus

planetary model

Bohr's model - electrons move around the nucleus in fixed, circular orbits

quantum model

Schrodinger's atomic model incorporating the wave aspect of matter and the probability of an electron's location

isotope

An atom with the same number of protons and a different number of neutrons from other atoms of the same element.

mass number

the sum of the number of neutrons and protons in an atomic nucleus

atomic mass unit

a unit of mass that describes the average mass of an atom's isotopes

energy levels (shells)

surround the nucleus and contain electrons (nucleus- protons and neutrons, 1st level- 2 electrons, 2nd level- 8 electrons, 3rd level- 8 electrons

Sublevels (s, p, d, f)

a portion of a principal energy level made up of one or more orbitals

orbitals

regions around the nucleus in which given electron or electron pair is likely to be found

principle quantum number

symbolized by n, indicates the main energy level occupied by the electron

s orbital

Spherical shape and can hold up to 2 electrons

p orbital

peanut shape with 3 orientations and holds a total of 6 electrons

d orbital

daisy shaped has 5 orientations and holds 10 electrons

f orbital

large flower shape has 7 orientations and holds 14 electrons

Aufbau Principle

An electron occupies the lowest-energy orbital that can receive it

Pauli Exclusion Principle

An atomic orbital may describe at most two electrons, each with opposite spin direction

Hund's Rule

orbitals of equal energy are each occupied by one electron before any orbital is occupied by a second electron, and all electrons in singly occupied orbitals must have the same spin

electron configuration

the arrangement of electrons in the orbitals of an atom

orbital notation

uses arrows pointing up or down to represent the electrons

atomic emission spectrum

the set of frequencies of the electromagnetic waves emitted by atoms of the element

Mendeleev

Russian chemist who developed a periodic table of the chemical elements and predicted the discovery of several new elements

periodic table

A chart of the elements showing the repeating pattern of their properties

groups/families

Vertical columns on the periodic table

periods

Horizontal rows on the periodic table

metals

Elements that are good conductors of electric current and heat.

nonmetals

Elements that are poor conductors of heat and electric current

metalloids

Elements that have properties of both metals and nonmetals.

alkali metals

Group 1, 1 electron in outer level, very reactive, soft, silver, shiny, low density; Lithium, Sodium, Potassium, Rubidium, Cesium, Francium

alkaline earth metals

metallic elements in group 2 of the periodic table which are harder than the alkali metals and are also less reactive

transition metals

Groups 3-12, 1-2 electrons in the outer energy level, less reactive than alkali-earth metals, shiny, good conductor of thermal energy and electrical current, high density

noble gases

the elements in Group 8A of the periodic table

atomic radius

one-half the distance between the nuclei of two atoms of the same element when the atoms are joined, trend increases down a group & decreases across a period

electronegativity

the ability of an atom to attract electrons when the atom is in a compound, trend increases across a period & decreases down a group

ionization energy

The amount of energy required to remove an electron from an atom, decreases from top to bottom in a group; increases from left to right in a period