ARRANGEMENT OF ELEMENTS.pdffffffffffffffffffffff

ARRANGEMENT OF ELEMENTS.pdf

1. ARRANGEMENT OF ELEMENTS

2. In the previous lesson..
The modern periodic table used in 21st Century
is far more advanced in terms of the number of
elements included and the manners in which they
are systematized. The gap’s in Mendeleev’s
original chart have been filled and more features
of the elements have been identified.

3. The most observable arrangements in the table are
rows and columns.
Each row and columns. Each row is
called a period or a series and each
column is known as a group or a family.

4. PERIODIC TRENDS
Periodic trends are specific patterns
that are present in the periodic table
that illustrate different aspects of a
certain element, including its size and
its electronic properties.

5. 1.ATOMIC RADII
-It is the distance from the center to the edge of the
shape.
-The wider the space between them, the larger the atom
is.
-Atomic size is measured through an atom’s radius, but
take note that atomic radii are not fixed.

7. 3 reasons why atomic radii are not fixed:
Electron Cloud Distribution:
●In quantum mechanics, electrons are not
confined to fixed orbits but exist in probability
regions known as orbitals. The uncertainty in the
exact position of electrons results in a dynamic
electron cloud, leading to a range of possible
atomic radii.

8. Electron Repulsion and Shielding:
●Electron-electron repulsion
causes the electron cloud to
expand as the number of
electrons increases.

9. Chemical Bonding and Molecular
Environments:
●Atomic radii can change based on
the chemical environment and the
type of chemical bonding present.

10. TWO TYPES OF ATOMIC BONDING
IONIC BONDS - involves the transfer of one or
more electrons from an atom to another.

COVALENT BONDS - is one which pairs of
electrons are shared by atoms.

11. 2. IONIZATION ENERGY
-It is the lowest amount of energy required to
make this happen (the tendency to break free
from the atom once they reach a specific amount
of energy)
-Occurs because the valence electrons that are
removed from their subshells leave behind a
positively-charged ion or cation.

12. -If the ionization energy is high, the outermost
electron requires more energy to pull away from
the subshell.
-If the ionization is low, the outermost electron
requires less energy to move away from the shell.
-The more attracted the outermost electron is to
the nucleus, the higher the ionization energy.

13. FIRST IONIZATION ENERGY - amount of energy
that removes the first valence electron.
SECOND IONIZATION ENERGY - the energy
removes a second electron.
This trend is expressed in units of kilojoule per
mole (kJ/mol)

14. -Left to right and bottom to top the ionization
energy increases.
-Helium has the GREATEST ionization energy in
period 1 and group 18 of the periodic table.
-Electrons in the inner shells shield the outer
electrons from the nucleus, when this happens
the outer electrons repel the inner electrons and
extend the atomic radius. This is called electron
shielding.

15. 3. METALLIC AND NON METALLIC CHARACTERS
METALLIC PROPERTY - refers to the tendency of their
atoms to lose valence electrons and forms cations.
NONMETALLIC CHARACTER - moving from left to right
across periods highlights the nonmetallic character of
elements because the right side of the table consists
mostly of gases and other nonmetals.

17. 4. ELECTRON AFFINITY
-A gaseous atom’s tendency to accept or receive
electrons and produce a negatively-charged.
-Focused on gaining electrons resulting in anions,
the negatively-charged atom.
-EA is expressed in units of kJ/mol.
-Electron affinity manifests in two ways; The
EXOTHERMIC and ENDOTHERMIC

18. Exothermic Reaction:
●Definition: An exothermic reaction occurs when an
atom accepts an electron, and energy is released in
the form of heat.
Endothermic Reaction:
●Definition: An endothermic reaction occurs when an
atom accepts an electron, and energy is absorbed
from the surroundings.

19. 5. ELECTRONEGATIVITY
-Refers to the inclination of an atom to attract
the shared electrons of bonded atoms.
-If an atom is more electronegative, electrons are
more attracted to it.
-The value for electronegativity is commonly
found in the upper right corner of each element
in the periodic table.

22. ELEMENT BLOCKS
-Elements are also arranged and classified
according to the shape of their atomic orbitals.
-As previously mentioned, the orbitals are
identified through the letters s, p, d, and f.
-The same letters are used in naming blocks of
elements with similar atomic orbital shapes.

23. S-BLOCK is composed of the first and second groups
(also known as the alkali and alkaline earth metals) as
well as hydrogen and helium

24. D-BLOCK is composed of transition metals. These
elements have low electronegativity and can lose
electrons just as easily as the s-block element.

25. P-BLOCK is the rightmost block which covers groups
13 to 18 and consists of metallic and gaseous
elements.

26. F-BLOCK is composed of the lanthanide and actinide
series which are extensions of the transition metals.