Atomic Strucure And Periodic Table Flashcards
What are the three subatomic particles in an atom?
Protons, neutrons, and electrons.
What is the charge of a proton?
+1 (positive).
What is the charge of a neutron?
0 (neutral).
What is the charge of an electron?
-1 (negative)
Where are protons and neutrons found in an atom?
In the nucleus.
Where are electrons found in an atom?
In energy levels (shells) around the nucleus.
What is the atomic number of an element?
The number of protons in an atom.
What is the mass number of an atom?
The total number of protons and neutrons in an atom.
How do you calculate the number of neutrons in an atom?
Mass number - Atomic number.
What are isotopes?
Atoms of the same element with the same number of protons but different numbers of neutrons.
What determines the chemical properties of an element?
The number of electrons in the outer shell.
Why are noble gases (Group 0) unreactive?
They have a full outer electron shell.
Who first proposed the idea of atoms?
John Dalton in the early 19th century.
What did J.J. Thomson discover?
The electron, leading to the “plum pudding model” of the atom.
What experiment did Rutherford and Marsden conduct?
The gold foil experiment.
What did Rutherford’s experiment show about the atom?
It has a small, dense, positively charged nucleus, with electrons orbiting around it.
How did Bohr improve Rutherford’s model?
He proposed that electrons orbit the nucleus in fixed energy levels (shells).
What did James Chadwick discover?
The neutron, explaining the missing mass in atoms
How are electrons arranged in an atom?
In energy levels (shells).
What is the maximum number of electrons in the first shell?
2 electrons
What is the maximum number of electrons in the second and third shells?
8 electrons each.
How do you determine an element’s group number from its electronic structure?
The number of electrons in the outer shell.
How do you determine an element’s period number from its electronic structure?
The number of electron shells.
What is the electronic structure of sodium (atomic number 11)?
2, 8, 1.
Why do elements in the same group have similar chemical properties?
They have the same number of electrons in their outer shell.
Who developed the modern periodic table?
Dmitri Mendeleev in 1869
How did Mendeleev arrange the elements in the periodic table?
By atomic mass, but he also grouped elements with similar properties together.
Why did Mendeleev leave gaps in his periodic table?
For undiscovered elements that he predicted based on patterns.
How is the modern periodic table arranged?
By atomic number (number of protons).
What are groups in the periodic table?
Vertical columns containing elements with similar chemical properties.
What are periods in the periodic table?
Horizontal rows that show the number of electron shells.
What are the main types of elements in the periodic table?
Metals (left side) and non-metals (right side).
What is a metalloid (semi-metal)?
An element that has properties of both metals and non-metals (e.g., silicon).
What are the properties of alkali metals?
Soft, low-density, highly reactive, and have low melting points.
How does reactivity change as you go down Group 1?
Reactivity increases because the outer electron is further from the nucleus and is more easily lost.
What happens when alkali metals react with water?
They form a metal hydroxide and hydrogen gas.
What is the word equation for sodium reacting with water?
Sodium + Water → Sodium Hydroxide + Hydrogen.
Why are alkali metals stored in oil?
To prevent them from reacting with oxygen and moisture in the air
What are the properties of halogens?
Non-metals, diatomic molecules, and highly reactive.
How does reactivity change as you go down Group 7?
Reactivity decreases because the outer shell is further from the nucleus, making it harder to gain an electron.
What is the trend in boiling points of the halogens?
Boiling points increase as you go down the group.
What is a displacement reaction?
A more reactive halogen can displace a less reactive halogen from its compound
Give an example of a halogen displacement reaction.
Chlorine + Potassium Bromide → Potassium Chloride + Bromine.
What are the properties of noble gases?
They are unreactive, colorless gases with low boiling points.
Why are noble gases unreactive?
They have a full outer electron shell
How does boiling point change as you go down Group 0?
Boiling points increase due to stronger intermolecular forces.
