Topic 1b - The Periodic Table Flashcards
How are elements organised in the periodic table?
The elements in the periodic table are arranged in order of atomic (proton) number and so that elements with similar properties are in columns, known as groups.
Why is it called the periodic table?
The table is called a periodic table because similar properties occur at regular intervals.
Why do elements in the same group have similar chemical properties?
Elements in the same group in the periodic table have the same number of electrons in their outer shell (outer electrons) and this gives them similar chemical properties.
How did scientists attempt to classify elements before the discovery of protons, neutrons and electrons?
Before the discovery of protons, neutrons and electrons, scientists attempted to classify the elements by arranging them in order of their atomic weights + physical/chemical properties.
How did John Newland arrange his periodic table?
By atomic mass but there were many mistakes and inconsistencies.
What was wrong with early periodic tables?
The early periodic tables were incomplete and some elements were placed in inappropriate groups if the strict order of atomic weights was followed.
How did Dimitri Mendeleev overcome some of the problems of the early periodic table and when?
- In 1869, Dimitri Mendeleev overcame some of the problems of the early periodic tables by taking 57 known elements + arranging them into his Table of Elements, leaving various gaps.
- He put the elements, mainly in order of atomic weight but did switch the order of some elements if the properties mean it should be changed.
- Gaps were left in the table to make sure elements with similar properties remained in the same groups. He was able to predict some new elements, which later on proved to be correct.
When were isotopes discovered and how did this impact Mendeleev’s periodic table?
- Early 20th century
- Confirmed Mendeleev was correct not to place elements in a strict order of atomic weight but to also take into account their properties.
- Because isotopes of the same element have different masses but the same chemical properties so occupy the same position on the periodic table.
What are metals?
Elements that react to form positive ions are metals. The majority of elements are metals.
What are non-metals?
Elements that do not form positive ions when they react are non-metals. They either form negative ions, or they covalently bond with other non-metals.
Where are metals found on the periodic table?
Metals are found to the left and towards the bottom of the periodic table.
Where are non-metals found on the periodic table?
Non-metals are found towards the right and top of the periodic table.
What are the elements in Group 1 of the periodic table?
The elements in Group 1 of the periodic table are known as the alkali metals and have characteristic properties because of the single electron in their outer shell.
What happens to the reactivity of elements in group 1 as you go down the group?
In Group 1, the reactivity of the elements increases going down the group, because outer shells are further away from the nucleus - have a stronger negative charge.
What happens to the Ar as you go down the group 1 elements?
Relative Atomic Mass increases down the group.
How do the group 1 metals react with nonmetals?
Form ionic compounds
