chemistry Flashcards
What are atoms
Atoms are the smallest units that make up particles and are the smallest units of matter.
What are elements
An element is a substance that is made up of only one type of atom.
What are molecules
A molecule is two or more of the same atom chemically bonded together in a discrete unit (some elemnts exist as molecules e.g. o2)
What are compounds?
A compounds is two or more atoms of different elements bonded together.
What are molecular compounds?
A molecular compound consists of two or more non-metals chemically bonded in a discrete unit.
What are lattice compounds.
Lattice compounds are a system of atoms of different elements that are connected to all the atoms around them.
What is a pure substance
A pure substance is made up of only one type of particle and cannot be separated by physical means.
What is a mixture
A mixture is a substance made from two or more pure substance that have been put together (not chemically bonded) and can be physically separated.
what are atoms made up of?
Atoms are made up of a nucleus and an electron cloud
What are the three types of subatomic particles and what are their charges
Electrons:-ve
Protons:+ve
Neutrons no charge (neutral)
Where are the subatomic particles located?
Electrons: electron cloud
Protons: nucleus
Neutrons: nucleus
Does the atom have a charge?
The atom itself does not
What does the atomic number tell you?
The atomic number tells you how many protons there are. (This is equal to the number of electrons unless it is an ion and the position in the table)
How can you work out the amount of neutrons with the mass and atomic number?
Mass number - atomic number = neutrons
what are isotopes?
Isotopes are atoms that have the same number of protons (same element) but different numbers of neutrons. This means that isotopes of an element have different sized nuclei, which then makes some isotopes unstable and radioactive.
What do all the elements in the same group (column) in the periodic table have in common?
Similar properties because same number of electrons in their outer electron shells. Forms ion with the same charge.
What do all the elements in the same period (row) in the periodic table have in common?
elements in the same period have the same number of electron shells.
What is meant by “a neutral atom”? What is the relationship between the number of protons and electrons in a neutral atom?
The number of electrons and protons are the same in a neutral atom. E.g. Beryllium, it has 4 protons and 4 electrons. This means the protons and electrons cancel each other to make the atom neutral.
which subatomic particle gives an atom its mass.
protons and neutrons.
which part of the atom determines the atom’s size
electron cloud.
Describe what valence electrons are and how we determine how many valence electrons there are.
The electrons in the outermost shell of an atom are the valence electrons. Using the rule for how many electrons fit in each shell (2,8,8) and the atomic number you can determine #valence electron. Or look at which group it is in.
Define what an ion is and explain the difference between a cation and an anion using examples.
An ion is an atom that has gained or lost electrons and is now charged because the # of electrons and protons is no longer equal.
Which group of elements do not become ions and do they not form ions?
Noble gases e.g. Neon.
They do not form ions because they have a full outer shell and are already stable.
What are ionic bonds?
An ionic bond forms between positive metal cation and negative non-metal anions.
What is a polyatomic ion?
A polyatomic ion is an ion made up of 2 or more different atoms
State the Law of conservation of mass. How does it apply to chemical reactions?
Matter cannot be created or destroyed during a chemical reaction. Atoms are rearranged to form new substances but the mass of the reactant will equal the mass of the products, number of atoms in reactants will equal the number of atoms in products
