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Periodic Trends 6.3
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Periodic Trends
Sodium chloride (table salt) produced the geometric pattern in the photograph. Such a pattern can be used to calculate the position of nuclei in a solid. You will learn how properties such as atomic size are related to the location of elements in the periodic table.
6.3
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Periodic Trends >
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Trends in Atomic Size
Trends in Atomic Size
What are the trends among the elements for atomic size?
6.3
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Periodic Trends > Trends in Atomic Size
The atomic radius is one half of the distance between the nuclei of two atoms of the same element when the atoms are joined.
6.3
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Slide 5 of 31
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Periodic Trends > Trends in Atomic Size
Group and Periodic Trends in Atomic Size
In general, atomic size increases from top to bottom within a group and decreases from left to right across a period.
6.3
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Periodic Trends > Trends in Atomic Size 6.3
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Periodic Trends > Trends in Atomic Size 6.3
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Periodic Trends >
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Ions
Ions
How do ions form?
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Periodic Trends > Ions
Positive and negative ions form when electrons are transferred between atoms.
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Periodic Trends > Ions
Positive and negative ions form when electrons are transferred between atoms.
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Periodic Trends > Ions
Some compounds are composed of particles called ions.
• An ion is an atom or group of atoms that has a positive or negative charge.
• A cation is an ion with a positive charge.
• An anion is an ion with a negative charge.
6.3
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Periodic Trends > Ions
Animation 7
Discover the ways that atoms of elements combine to form compounds.
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Periodic Trends >
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Trends in Ionization Energy
Trends in Ionization Energy
What are the trends among the elements for first ionization energy, ionic size, and electronegativity?
6.3
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Periodic Trends > Trends in Ionization Energy
The energy required to remove an electron from an atom is called ionization energy.
• The energy required to remove the first electron from an atom is called the first ionization energy.
• The energy required to remove an electron from an ion with a 1+ charge is called the second ionization energy.
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Slide 15 of 31
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Periodic Trends > Trends in Ionization Energy
Group and Periodic Trends in Ionization Energy
First ionization energy tends to decrease from top to bottom within a group and increase from left to right across a period.
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Periodic Trends > Trends in Ionization Energy 6.3
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Periodic Trends > Trends in Ionization Energy 6.3
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Periodic Trends > Trends in Ionization Energy 6.3
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Periodic Trends > Trends in Ionic Size
Trends in Ionic Size
During reactions between metals and nonmetals, metal atoms tend to lose electrons, and nonmetal atoms tend to gain electrons. The transfer has a predictable effect on the size of the ions that form.
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Periodic Trends > Trends in Ionic Size
Cations are always smaller than the atoms from which they form. Anions are always larger than the atoms from which they form.
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Slide 21 of 31
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Periodic Trends > Trends in Ionic Size
Relative Sizes of Some Atoms and Ions
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Periodic Trends > Trends in Ionic Size
Trends in Ionic Size
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Slide 23 of 31
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Periodic Trends > Trends in Electronegativity
Trends in Electronegativity
Electronegativity is the ability of an atom of an element to attract electrons when the atom is in a compound.
In general, electronegativity values decrease from top to bottom within a group. For representative elements, the values tend to increase from left to right across a period.
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Periodic Trends > Trends in Electronegativity
Representative Elements in Groups 1A through 7A
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Periodic Trends >
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Summary of Trends
Summary of Trends
What is the underlying cause of periodic trends?
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Periodic Trends > Summary of Trends
The trends that exist among these properties can be explained by variations in atomic structure.
6.3