# Understanding Periodic Table Trends

• StephenDoty
In summary: The radius of an atom decreases as the element gets bigger. This is because the nucleus of an atom gets bigger and the electrons in the outer shells are further away from the nucleus. This means the atom has less negative electron affinity and is less reactive.
StephenDoty
Hello everyone. I am currently studying the periodic trends in my chemistry I class. So I just want to make sure I understand the concepts.

Z effective= Atomic # - # of core electrons.
Z increases across a row and doesn't really change going down a group.

Size, radius, of atoms
the radius decrease from left to right and increase going down a group.

Ionization energies
Increases from left to right and from bottom to top of a group

electron affinity
becomes increasingly negative going from left to right and doesn't really change going down a group but can become increasingly negative going up a group

Reactivity
decreases going from left to right since ionization energies increase going left to right
and increases going down a group since ionization energies decrease going down a group.

Z (atomic number) represents the number of protons (and + charges) in the nucleus of an atom, and in a neutral atom there is a equal number of electrons surrouding the nucleus. It is the electrons in the outermost 'shells' of the atom, i.e. those electrons that are most weakly bound, that determine the chemical properties of the atom (element).

Atomic mass is related to the total number of nucleons (protons and neutrons) in the nucleus of an atom. The atomic mass does not equal the mass of an equivalent number of nucleons because nucleons give up some energy (binding energy) when they combine to form more complex nuclei.

In the standard periodic table, Z increases from left to right, and from top to bottom.

This is a really good site for studying the periodicty of properties of the elements:
http://www.webelements.com/
http://www.webelements.com/periodicity/

e.g. http://www.webelements.com/periodicity/electron_affinity/

do the chapter 23 Thermochemistry

Astronuc said:
Z (atomic number) represents the number of protons (and + charges) in the nucleus of an atom, and in a neutral atom there is a equal number of electrons surrouding the nucleus. It is the electrons in the outermost 'shells' of the atom, i.e. those electrons that are most weakly bound, that determine the chemical properties of the atom (element).

Atomic mass is related to the total number of nucleons (protons and neutrons) in the nucleus of an atom. The atomic mass does not equal the mass of an equivalent number of nucleons because nucleons give up some energy (binding energy) when they combine to form more complex nuclei.

In the standard periodic table, Z increases from left to right, and from top to bottom.

This is a really good site for studying the periodicty of properties of the elements:
http://www.webelements.com/
http://www.webelements.com/periodicity/

e.g. http://www.webelements.com/periodicity/electron_affinity/

nuc

Why does A and Z diverge as the elements get bigger?

## 1. What is the periodic table?

The periodic table is a tabular arrangement of the chemical elements, organized by their atomic number, electron configuration, and chemical properties. It is a useful tool for understanding and predicting the behavior and properties of different elements.

## 2. What are periodic table trends?

Periodic table trends refer to the patterns and trends that can be observed in the properties of elements as you move across a row or down a column of the periodic table. These trends can help scientists understand the relationships between different elements and make predictions about their behavior.

## 3. What is the significance of periodic table trends?

Understanding periodic table trends allows scientists to predict the properties and behavior of elements based on their position in the table. This knowledge is essential in fields such as chemistry, materials science, and even medicine, where different elements and their properties play a crucial role.

## 4. What are some common periodic table trends?

Some common periodic table trends include atomic radius, electronegativity, ionization energy, and electron affinity. These properties typically increase or decrease in a predictable pattern as you move across a row or down a column of the periodic table.

## 5. How can I use periodic table trends in my research or experiments?

Periodic table trends can be used to make predictions about the properties and behavior of elements in your research or experiments. By understanding the trends, you can select the appropriate elements and conditions to achieve your desired outcome and interpret your results accurately.

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