Matter UnitLearning Goal #5: Compare the different number of protons, neutrons, and electrons of an atom in terms of ions, isotopes, and compounds.

Structure of An Atom

Remember… Atomic Number is the number of protons in

an atom. The number of protons equal the number of

electrons in a neutral atom.

Atomic Mass is the sum of the protons and neutrons in an atom. 6p+ + 6n0 = 12 (atomic mass of carbon)

Ions A charged entity.

This occurs if the number of electrons do not equal the number of protons.

This only occurs when an electron is added or removed from an atom.

The number of protons never change.

Ions

•An atom will gain or lose electrons to become more stable.

Cations cation – ion with a positive charge. If a

neutral atom loses one or more electrons

it becomes a cation.

Na 11 protons11 electrons

Na+ 11 protons10 electrons

Anions ion with a negative charge. If a neutral

atom gains one or more electrons it becomes an anion.

Cl 17 protons17 electrons Cl-

17 protons18 electrons

Atomic Radii

Li

Na

K

Rb

Cs

ClSPSiAl

BrSeAsGeGa

ITeSbSnIn

Tl Pb Bi

Mg

Ca

Sr

Ba

Be FONCB

1.52 1.11

1.86 1.60

2.31 1.97

2.44 2.15

2.62 2.17

0.88 0.77 0.70 0.66 0.64

1.43 1.17 1.10 1.04 0.99

1.22 1.22 1.21 1.17 1.14

1.62 1.40 1.41 1.37 1.33

1.71 1.75 1.46

IA IIA IIIA IVA VA VIA VIIA

= 1 Angstrom

0.60 0.31

0.95 0.65

1.33 0.99

1.48 1.13

1.69 1.35

1.71 1.40 1.36

0.50 1.84 1.81

0.62 1.98 1.85

0.81 2.21 2.16

0.95

IA IIA IIIA IVA VA VIA VIIA

= 1 Angstrom

Li1+ Be2+

Na1+ Mg2+

Ba2+

Sr2+

Ca2+K1+

Rb1+

Cs1+

Cl1-

N3- O2- F1-

S2-

Se2- Br1-

Te2- I1-

Al3+

Ga3+

In3+

Tl3+

Ionic Radii

• A monatomic ion contains only one atom Na+, Cl-, Ca2+, O2-, Al3+, N3-

A polyatomic ion contains more than one atom

OH-, CN-, NH4+, NO3-

Oxidation State of Elements

Se2-

Te2-

1

2

3

4

5

6

1

2

3

4

5

6

Al3+

Zn2+

Ag1+

N3- O2- F1-

Cl1-S2-

Br1-

I1-

Per

iod

Be2+

Na+

K+

Rb+

Cs+ Ba2+

H+

Li+

Ca2+

Sr2+

Mg2+

Group 1

2 13 14 15 16 17

18

NOBLE

GASES

Transition metals

A A MOLECULEMOLECULE is is 2 more atoms 2 more atoms bonded together – bonded together – they may be the same element (ie diatomic they may be the same element (ie diatomic molecule) or they may be different elements (ie molecule) or they may be different elements (ie caffeine)caffeine)

Composition of molecules is given by aComposition of molecules is given by a MOLECULAR MOLECULAR FORMULAFORMULA

HH22OO CC88HH1010NN44OO22 - caffeine - caffeine

Compounds

composed of 2 or more elements in a fixed ratio

properties differ from those of individual elements

EX: table salt (NaCl)

Ionic Compound ionic compounds consist of a cation and

an anion. The sum of the charges on the cation and anion in each

compound must equal zero.

The ionic compound NaCl

How to Combine Ions Na+1

Cl-1

Mg+2

Al+3

NaCl

The charges need to equal zero in a compound. +1-1=0

Mg3Al2

+2+2+2-3-3=0 3 Mg atoms are needed and 2 Al atoms are needed to get the overall charge to equal zero.

The charges need to equal zero. You may have more than one atom of each element to get the total charge of the compound to equal zero.

Naming Cations NAMING: The atomic cations are named

just like the neutral element followed by the word ion: For example: K+ is the potassium ion

MULTIPLE IONS: To distinguish the atomic ions Fe3+ from Fe2+ we name them iron(III) ion and iron(II) ion

Naming Anions The simplest negative ions, consisting of a

single atom of a given element. Use the root of the element’s name and add -ide

to get the name of the most common anion. Examples are:

(1st row): H- is the hydride ion (2nd row): N3- is the nitride ion ; O2- is the oxide ion ; F- is

the fluoride ion (3rd row): P3- is the phosphide ion; S2- is the sulfide ion;

Cl- is the chloride ion

Polyatomic IonsYou must memorize the names of common polyatomic ions

IsotopesIsotopes

Atoms of the same element (same Z) but different mass number (A).

Boron-10 (10B) has 5 p and 5 n Boron-11 (11B) has 5 p and 6 n

10B

11B

Isotopes & Isotopes & Their UsesTheir Uses

Bone scans with radioactive technetium-99.

IsotopesIsotopes Isotopes are atoms of the same element having different masses due to varying numbers of neutrons.Isotope Proto

nsElectron

sNeutron

sNucleus

Hydrogen–1

(protium)

1 1 0

Hydrogen-2

(deuterium)

1 1 1

Hydrogen-3

(tritium)

1 1 2

Lithium has an atomic mass of 6 and an atomic number of 3.

This isotope of Lithium has 3 neutrons.

Atomic Symbols

Show the name of the element, a hyphen, and

the mass number in hyphen notation

sodium-23

Show the mass number and atomic number in

nuclear symbol formmass number 23 Na

atomic number 11

Isotopes? Which of the following represent

isotopes of the same element?

Which element is it?

234 X 234

X235

X238

X

92 93 92 92

1 2 3 4

CARBON-14 – RADIOACTIVE ISOTOPE

Occurs in trace amounts in the atmosphere

Absorbed into living organisms The half-life of carbon-

14 is approx 5700 years (when half the C-14 is converted to N-14)

All green plants maintain a constant level of carbon 14 while alive. Once the plant dies, the carbon 14 starts to deteriorate at a precise rate that is well documented and measurable, via the use of calibration curves. Using the remaining carbon 14 the date that the plant died can be worked out. The date is not totally precise and can vary up to at least fifty years of the year obtained from the results.