Chapter 2: Matter, Atoms, & Atomic Structures

Three fundamental units of measure quantities

Mass - Kilogram

Length - Meter

Time - Second

Mass is

the quantity of matter in a body

Kilogram is measured on

the mass of 1,000cm³ of water at 4* Celsius

Weight is

a result of gravitational force on a body

Weight varies if

g force varies

mass remains

constant even if g force changes

What is an Element?

i.e. the atom - basic building block for all substances (simple substance)

What is a compound?

2 or more elements chemically combined (complex substance)

What is the smallest part of a compound?

A molecule

What is a molecule?

two or more atoms chemically unite

What is radiation?

When energy is emitter and transferred through matter

All matter is

made of atoms

What are the fundamental particles of an atom

Neutron

Proton

Electron

What is the weight of a Neutron?

1.008 amu

What is the weight of a Proton?

1.007 amu

What is the weight of an Electron?

5.48 × 10^-4 amu

Protons and Neutrons are how many times bigger than an electron?

2000

The nucleus of an atom contains

two subatomic particles, protons(+) and neutrons(o)

Electron shells are arranged in order

from K shell to Q shell

What is most of the space in atom?

empty

Atoms first introduced by the Greeks?

Air, Earth, Fire, Water

What did Niels Bohr’s Bohr Model first introduce?

The concept of the atom with orbiting electrons

Shell closest to nucleus that can only hold 2 electrons?

K shell

Shell number aka

Principle Quantum Number

Equation for how many electrons allowed in a shell?

2n²

What is the octet rule?

The outer shell of a stable atom cannot hold more than 8 electrons

What is the name of the outermost layer of an Atom?

Valence Shell

What does having 8 electrons on a a valence shell signify?

very stable, chemically inert

What is Electron binding energy?

How tightly the electron is held in its shell

Electrons are held tightly together due to

electrostatic attraction (opposites attract)

The closer a shell is to the nucleus the

greater the binding energy

What unit is electron energy?

KeV (KiloElectron Volt)

Definition of Ionization?

Adding or removing an electron from its shell

If an electron is added

termed a negative ion

If an electron is removed

termed a positive ion

Electrons become excited by

either collision or absorption, and move to another higher energy state (shell)

Atomic Mass is

number protons and neutrons in an atom

Atomic Number is

number of protons in the nucleus of an atom

Changing the number of protons =

changing the element

How many naturally occurring elements?

92

How many artificially produced atoms?

26

Atoms in the periodic table are arranged by

their atomic number (Z#)

How are Rows/Periods in the periodic table arranged?

Increasing Z#

Having the same amount of energy shells

How are Columns/Groups arranged in the periodic table?

Similar chemical properties

Same number of electrons in valence shell (outer electron configuration)

Isotopes

Atoms of the same element whose nuclei contain the same number of protons but a different number of neutrons

(Therefore, have different MASS NUMBERS)

Isobar

Atoms of different elements that have different atomic numbers but same mass number

Isotone

elements with same number of neutrons

Radioisotopes (aka radioactive isotopes)

unstable isotopes that spontaneously transform into different elements

Radioactive Decay

The transformation of radioactive nuclei into a different element

How is radioactive decay measured?

Bq

Half-Life

Time required for a radioisotope to decay to one-half of its activity (unique to its radioisotope)