B1- Core Science Concepts (Chemistry) Flashcards
How were the elements in the early periodic table arranged?
Newland’s arranged elements in increasing order of atomic mass
How are elements arranged in the modern periodic table?
Arranged in order of increasing atomic number in rows and periods.
What is the general name for the unreactive elements in the periodic table?
The noble gases
Why do metals get more reactive going down a group?
The attraction between the nucleus (of the atoms) and the outer shell electrons gets weaker
Where are the transition metals found?
Groups 3-12 of the periodic table
Why do the halogens have low melting and boiling points?
Because the forces of attraction between the molecules are weak
Why are the elements in group 1 called the ‘alkali metals’ ?
When they react with water they become an alkali
Why are the noble gases so unreactive?
The atoms of noble gases already have a complete outer shell
Why did Mendeleev leave gaps in his periodic table?
For the discovery of new elements
What are the three types of sub-atomic particle?
Proton, neutron and electron
What are the differences between the plum pudding model and the nuclear model?
Plum pudding - space between electrons is positively charged “soup”
Nuclear model - mostly empty space
Who proposed the plum pudding model?
JJ Thomson
How does a positive ion form?
Atoms colliding with an energetic electron
when an atom loses an electron
How many protons, neutrons and electrons are there in an atom of aluminium (AN=13 MN=27) ?
13 protons
13 electrons
14 neutrons
Which law states that the mass of products formed in a reaction is equal to the mass of reactants?
The law of conservation of mass
Why do elements in a group have similar chemical properties?
Because they have the same number of electrons in the outershell
What determines the order of the elements in the periodic table?
The elements atomic number
What type of substances are shown in the periodic table?
Elements