atomic structure

• Electrons are negatively charged particles that orbit around the nucleus of an atom.
• The number of protons is equal to the number of electrons, so atoms are electrically neutral.
• Protons are positively charged particles found in the nucleus of an atom.
• The number of electrons is equal to the number of protons, making atoms electrically neutral.
• Protons have a positive charge (+1) while neutrons do not carry any electrical charge (0).
• The number of protons determines the element's identity (atomic number).
• Atoms with different numbers of neutrons but the same number of protons belong to the same element.
• Isotopes are atoms of the same element with different masses due to varying numbers of neutrons.
• Isotopes are different forms of the same element that contain the same number of protons but differing numbers of neutrons.
• Atoms with different numbers of neutrons are called isotopes.
• Electrons orbit around the nucleus at various distances from it.
• A nucleus contains both protons and neutrons.
• An atom can be represented by its chemical symbol, which consists of one or two letters representing the name of the element.
• An atom can be represented by its chemical symbol or as an electron dot diagram.
• An electron has a negative charge (-1), a proton has a positive charge (+1), and a neutron does not have any charge.
• Protons and electrons balance out their charges within an atom.
• Mass number = number of protons + number of neutrons
• The average mass number of the isotopes of an element is called its relative atomic mass (RAM).
• RAM = (mass number x abundance )x (mass number x abundance)/ total abundance (100)
• Chlorine- 35 (75%) Chlorine- 37 (25%)

  RAM = (75x35)x(25x37)/100 = 35.5
• Fluorine isotopes - 19 (80%)

  - 22 (15%)

  - 23 (5%)

  RAM= 19.7
• one mole - of any substance- will have a mass in grams equal to the relative formula mass (Ar or Mr)
• relative formular mass = the amount of atoms in the substance/ compound e.g. CO2 = 12 +(2x16)=44
• How many moles are there in 66g of CO2?

  66/44= 1.5 mol
• no. of moles= mass in g (of element or compound)/ relative formular mass (Mr)(of element or compound)
• one mole = relative atomic/ formular mass in grams of element/ compound.