Atomic Structure and Electron Arrangement

• Write correct symbols and names of some elements• Describe the physical properties of some elements• Categorize an element as a metal or non-metal from its physical properties• Describe the color of a flame produced by an element• Draw a model of an atom including the electron arrangement for the first

20 elements

The Atom• All matter on Earth is made from atoms• Atoms are really tiny less than a billionth of a meter across• Only been imaged in recent decades• Too small to see with visible light

The Atom

• The atom is made up of 3 subatomic particles

• The Proton• The Electron• The Neutron

• The atom has a nucleus (made up of protons and neutrons)

• The electrons exist as waves in a cloud around the nucleus

The Atom

The Elements

• There are 98 naturally occurring elements, (the first 98)

• These are listed according to their atomic number Z

• Each element with a different atomic number is denoted by a Chemical Symbol – a one or two letter symbol – often Greek or Latin in origin and sometimes good ol’ English (C = Carbon, Si = Silicon, Br = Bromine etc)

• The elements are listed in a table, ordered in increasing atomic Number as one goes across and down the periodic table

• Elements in a given column share certain chemical properties that make them similar

Elements: Patterns and the Periodic Table

Elements: Patterns and the Periodic Table

Part A: The Elements• In Part A you will be becoming familiar with writing the Chemical symbol,

atomic number and physical properties for selected elements• The elements are defined by how many protons are in the nucleus• We call this the Atomic Number Z• Examples

– Helium has 2 protons– Hydrogen has 1 proton– Aluminum has 13 protons

Part B: The Elements

• In Part B – use the empty periodic table to– Write the atomic number and symbol for the elements

identified in part A– Write the group number at the top of each column– Write out the period numbers for each horizontal row– Use different colors to highlight, alkali metals, alkaline

earths, halogens, noble gases and transition metals– Draw a heavy line to separate metals from non-metals

Part C: Subatomic Particles

• In part C we look at the subatomic particles that make up atoms

• Atomic number Z = # protons = p+ = # electrons = e-

• Z defines what element we have• Mass Number = # of protons + # of neutrons =p+ + n0

Element AtomicNumber

MassNumber

Protons Neutrons Electrons

Iron 26 26+30=56 26 30 26

Aluminum 27-13=14 27 13 14 13

Part D: Isotopes

S34

16

Mass number = p+ + n0

Atomic Number Z = p+

Symbol of the Element

Nuclear Symbol Protons Neutrons Electrons

20 40-20 = 20 20

Part E: Flame Tests• When heats electrons in atoms and ions can be excited to higher energy

levels• When they cool down the electrons return to their ground state and release

energy as light• Group 1A and 2A elements produce colorful flames• The color of the flame is like a fingerprint for that element/ion• Discover the color of flames containing CaCl2, KCl, SrCl2, BaCl2, CuCl2 and

NaCl• Identify ions in the mystery solutions

Part F: Drawing Models of Atoms • The shape of the periodic table is connected to how the electrons are structured in

the atom• Electrons behave as waves sloshing back-and-forth• The different waves are called a orbitals• There are s, p, d, and f orbitals, s orbitals can fit 2e-, p 6e-, d 10e- and f 14e-

• The higher the energy of the electron the further it is from the nucleus on average

Row in Periodic Table

Number of electrons

Orbitals involved

1 2 1s

2 8 2s,2p

3 18 3s,3p,3d

Part F: Drawing Models of Atoms• In Part F you will be asked to draw out a simplified electronic structure for

certain elements in the following way

• First Row Atom • Fourth Row Atom