C2 Flashcards
How did Mendeleev initially arrange elements in the periodic table?
By their atomic weights
What happens to the boiling and melting points of alkali metals as you go down the group?
They decrease
List some properties of alkali metals:
-Low densities
-Soft
-React vigorously with oxygen
-Have low melting/boiling points
What are the products of a reaction between an alkali metal and water?
A metal hydroxide and hydrogen gas
List some properties of halogens:
-They have low melting/boiling points
-They are poor conductors
-7 outer electrons
-Exist as diatomic molecules
What happens to the boiling and melting points of halogens as you go down the group?
They increase
List some physical properties of transition metals:
-Good conductors
-High densities
-Hard/strong
-They have high melting points (except mercury)
-Can be used as catalysts
-They form coloured compounds
How do transition metals differ from alkali metals in reactivity?
They react a lot less readily with oxygen/water
List some differences between the plum pudding model and the nuclear model:
In the nuclear model:
-the atom is mainly empty space
-the mass is concentrated in the nucleus
-the positive charge is all in the nucleus
-the electrons are separate from the nucleus
How did Niels Bohr adjust the nuclear model?
He made the electrons orbit the nucleus at fixed distances
Why can we not measure the boiling point of a single molecule?
Boiling point is a bulk property, and is related to inter-molecular forces, so more than one molecule is involved
What state is astatine at room temperature?
Solid
Why did Mendeleev’s periodic table become more widely accepted?
Mendeleev had predicted properties of missing elements. When these elements were discovered, their properties matched Mendeleev’s predictions.
What property of hydrogen makes it potentially dangerous?
It is explosive
