Ch. 11.4 Notes---Atomic Properties and the Periodic Table

Valence Electrons and Electron Dot Notations

What are “valence electrons”?

• These are the electrons in the _________-_______ energy level (or shell). These are responsible for chemical bonding.

• All of the other electrons are called “core electrons”.

• They will be “___” electrons and “___” electrons only.

Counting Valence Electrons

• Group A # = number of valence electrons

(only exception Helium = __ e-’s)

Examples: Ca = __ e-’s Nitrogen = __ e-’s Argon = __ e-’s

• d-block and f-block = ___valence e-’s

outer most

s p

2 5 8

2

2

Drawing Valence Electrons

• “Electron-dot notation”: Electrons will be represented as dots located around the symbol of the element in the pattern shown below.

Examples: Nitrogen = Hydrogen =

(important exception.... Carbon = )

X 2

1

3

4

7

5 8

6

N H

C

The Development of the Periodic Table

• _________________________: constructed the 1st periodic table

Features of Mendeleev’s Periodic Table

• He left ______ _________ for “missing elements”. Later when these elements were discovered, he filled in the gaps.

• He arranged the elements in columns and rows according to their __________________. Elements with similar properties were in the same horizontal row.

• He was able to accurately ___________ the properties of the missing elements based on the properties of the elements in similar _______.

• He ordered the elements by increasing __________ ___________.

Dmitri Mendeleev

blank spaces

properties

predictrows

atomic mass

Features of the Modern Periodic Table

• In 1913, Henry ______________ determined the atomic number, (# of ___), of the elements.

– He then arranged the elements in the periodic table by increasing atomic ____________.

– This switched the position of some elements. This is how the modern periodic table is arranged today.

• Horizontal Rows = ____________ or Series

• Vertical Columns = ____________ or Families

• Elements in the same _________/_________ have similar properties.

Moseley

number

p+

Periods

Groups

groups families

Figure 11.35: Classification of elements as metals, nonmetals, and metalloids.

Parts of the Periodic Table

• Metals: located to the _______ of the dark zig-zag line running through the “p-block”. This includes the elements in the ___-block.

Properties of Metals

– shiny surface

– ______________ (you can pound it into a flat sheet)

– ______________ (you can draw it into a thin wire)

– good _______________ (heat/electricity travels through it easily)

leftf

malleable

ductile

conductors

Parts of the Periodic Table

• Nonmetals: located to the ___________ of the dark zig-zag line.

Properties of Nonmetals

– _______ surface

– ______________

– good _______________ (or poor conductors)

• Metalloids: located on the border of the dark zig-zag line.

Examples: Silicon & Germanium

Properties of Metalloids

– ___________________

right

dull

brittle

insulators

semiconductors (Used in computer chips)

sulfur

Parts of the Periodic Table• d-block metals: “_________________ metals”

• f-block metals: “Inner-transition metals” or “____________ metals”

Special Group/Family Names

• Group 1A: “_________ metals”

– React with _________ to form a base

• Group 2A: “________________ metals”

– Compounds are used in batteries

• Group 7A: “_________________”

– Used in some light fixtures

• Group 8A (or 0 or 18): “_______ gases”

– Don’t form compounds (_________)

transition

rare-earth

Alkali

water

Alkaline-earth

Halogens

Noble

inert

Parts of the Periodic Table

Inner-transition metals

Trends in the Periodic TableAtomic Size (Atomic Radius)

(See Fig. 11.36)

• Moving Down a Group= the size of the atoms ________________

– Why? You are adding ________ electrons to higher and higher energy levels (farther and farther out.)

• Moving Across a Period= the size generally ______________

– Why? You are adding more e- and p+ to the same energy level. This causes more ______________ of

opposite charges and it __________ the electron cloud inward.

increases

more

decreases

attractionpulls

Figure 11.36: Relative atomic sizes for selected atoms.

Trends in the Periodic TableAtomic Size vs. Ion Size

(See Figure 12.8)

• Cation = (___) charged atom created by ___________ e-’s.

– Cations are ______________ than the original atom.

– _____________ generally form cations.

• Anion = (___) charged atom created by _____________ e-’s.

– Anions are ____________ than the original atom.

– _______________ generally form anions.

+ removing

smaller

Metals

− adding

larger

Nonmetals

Trends in the Periodic TableAtomic Size vs. Ion Size

Figure 12.8: Relative sizes of some ions and their parent atoms.

picometers

Ionization Energy

• Ionization energy is the energy required to _______________ the outer most electron in an atom.

• Moving Down a Group= _______________ (less energy is needed)

– Why? You are trying to remove an electron that is farther and farther out (for larger and larger atoms).

These e-’s are not as ________________to the nucleus.

– In general, the larger the atom, the ____ attracted it is to its e-’s.

Trends in the Periodic Table

remove

decreases

attracted

less

Ionization Energy

• Moving Across a Period= generally ________________

– Why? Moving across a period takes us from metals to nonmetals. More ionization energy is needed for

______________ compared to __________.

– Also, since metals generally form _________, it won’t take as much energy to remove it’s outer most electron.

– Remember that as you move across the period, the atoms get _________ and therefore ______ attracted to the electrons.

Trends in the Periodic Table

increases

nonmetals metals

cations

smaller more

First Ionization Energies

“Successive Ionization Energies”

• “Successive Ionization Energies” means the energy required to remove a _____ or a _____ electron from an atom.

– Removing more and more e-’s requires ______ and ______ energy.

– Why? The remaining e-’s are more _________ _________ to the nucleus.

Trends in the Periodic Table

2nd 3rd

more more

tightly bound

Electronegativity

(See Figure 12.4)

• Electronegativity is a relative value (from_________) which compares how much an atom is attracted to the e-’s in a ____________ bond.

• Moving Down a Group= generally ______________ (less

attraction)

– Why? The bonded electron is farther and farther out. These e-’s will not be as attracted to the larger and larger atoms.

Trends in the Periodic Table

0 – 4.0

chemical

decreases

Figure 12.4: Electronegativity values for selected elements.

Electronegativity

• Moving Across a Period= generally _________________

– Why? Again, the atoms are getting ________ so they are _______ attracted to the bonding electrons.

– Also, moving across a period takes us from metals to nonmetals. Since nonmetals generally form _________, they tend to __________ e-’s anyway, and this makes them ________________ attracted to e-’s when forming a chemical bond.

– ___________ __________ are not listed in Figure 12.4 since they do not ________ _____________ !

Trends in the Periodic Table

increases

smaller more

anions gain

highly

Noble gases form compounds

Determining the Ion Formed• Atoms try to achieve a ________ ______ configuration when

forming an ion. (This makes them more stable.)

– Locate the nearest noble gas and count how many “places” it is away, but remember that you can skip over the d-block!!

– This amount will be the same as the # of e-’s either gained or lost by the atom when forming an ion.

Practice Problem: How many electrons are gained or lost when forming an ion from the following elements?

a) Magnesium: ____ (gained or lost) b) Iodine: ____ (gained or lost)

c) Gallium:____ (gained or lost) d) Boron:____ (gained or lost)

noble gas

2 1

3 3