Structure and Properties

of Matter

Earth Science-Chapter 3.1

What is an atom? the smallest particle of an element that has the

properties of that element

element = a substance that cannot be broken down

by ordinary chemical means to a smaller substance

building block of matter

Atoms are made of:

Protons (+)

Neutrons (neutral)

Electrons (-)

Most of the mass is concentrated in the nucleus

(location of protons & neutrons)

Atomic Structure

Nucleus contains the protons and neutrons

where most of the mass of the atom is concentrated

very dense

Electron Cloud the space around the nucleus in which electrons

move rapidly

not dense at all

divided into energy levels lower energy levels are closer to the nucleus and have less energy

Atomic Structure

atomic number =

number of protons

Silver has 47 protons

atomic mass = number

of protons + neutrons

Silver has 61 neutrons

valence electrons =

electrons in the

outermost energy level

Atomic Structure

Looking at the periodic table on page 271, answer the following questions: What element does

this atom represent?

How many valence electrons does this atom have?

How many neutrons does this element have according to the periodic table?

Isotopes

atoms of the same element having

different numbers of neutrons

identified with different mass numbers

mass number on the periodic table

averages the mass of all known isotopes

isotopes have the same chemical

properties

Periodic Table

left side = metals

most elements are metals

right side = non-metals

Groups/Families = columns; go up and down

Group number indicates # of valence electrons (outermost electrons)

Rows/Periods = side to side

Period number indicates # of electron energy levels

Figure Reference

Atomic Number figure: retrieved from

http://education.jlab.org/glossary/atomicn

umber.html

Atomic Structure figure: retrieved from

http://www.rstp.uwaterloo.ca/manual/mat

ter/atom_structure.htm

Periodic Table figure: retrieved from

http://www.cameco.com/uranium_101/fa

ct.php