Atoms, elements, compounds Flashcards
What are atoms?
They make up all substances and are the smallest part of an element
What are compounds?
Contain two or more elements chemically combined, which can only be separated by chemical reactions.
What is a mixture?
Consists or two or more elements or compounds not chemically combined together. The chemical properties of each substance in the mixture are unchanged.
How can mixtures be separated?
Filtration
Crystallisation
Simple distillation
Fractional distillation
Chromatography
What is the atomic number?
the number of protons in an atom
What do all atoms of a particular element share?
the same number of protons
What is the relative charge of a proton, neutron and electron?
proton: +1
neutron: 0
electron: -1
What is an atoms overall charge?
0
What is the mass number?
the sum of protons and neutrons in an atom
What are isotopes?
atoms of the same element with a different number of neutrons
What does the electronic structure of an atom tell you?
how many electrons are in each shell
What are ions?
Ions are atoms which have an overall charge. This is because they have gained or lost electrons
- Positive ions have lost electrons
- Negative ions have gained electrons
Shells: What are they and how many atoms can they hold?
- Electrons surround the nucleus in shells
- The shell closest to the nucleus can hold 2 electrons but the outer ones can hold 8
How many protons, neutrons and electrons are in this element:
35
Cl
17
17 protons
18 neutrons
17 electrons
What does the amount of electrons in the atom’s outer shell determine?
- What group the element is in: 1 electron = Group 1
- Atoms with a full outer shell are in Group 0
