Chemistry AQA a LEVEL AS PAPER 1 2024 UPDATE GRADED A+

Chemistry AQA a LEVEL AS PAPER 1 2024 UPDATE GRADED A+ what are the three fundamental particles that make up an atom? - CORRECT ANSWER-protons, neutrons and electrons nucleus - CORRECT ANSWER-- most of mass of atom is concentrated in the nucleus - the diameter of the nucleus is rather titchy compared to the whole atom - protons and neutrons are sometimes found in the nucleus electrons - CORRECT ANSWER-- electrons have a -1 charge - they surround the nucleus - the orbitals take up most of the volume of the atom mass and charge of these subatomic particles are really small, so relative mass and relative charge are usually used instead - CORRECT ANSWER-proton: relative mass- 1 relative charge- +1 neutron: relative mass- 1 relative charge- 0 electron: relative mass- 1/2000 relative charge- -1 mass number - CORRECT ANSWER-this tell you the number of protons and neutrons in the nucleus atomic (proton) number - CORRECT ANSWER-- number of protons in the nucleus- it identifies the element - all atoms of the same element have the same number of protons for neutral atoms - CORRECT ANSWER-- have no overall charge - number of electrons are the same as the number of protons - number of neutrons is mass number - atomic number, i.e. top minus bottom ions have different numbers of protons and electrons - CORRECT ANSWER-atoms form ions by losing or gaining electrons. negative ions have more electrons than protons Br- - CORRECT ANSWER-- negative charge means there's 1 more electron than there are protons - Br has 35 protons, so Br- must have 36 electrons - overall charge = +35 -36 = -1 positive ions have... - CORRECT ANSWER-fewer electrons than protons Mg^2+ - CORRECT ANSWER-- 2+ charge means that there are 2 fewer electrons than there are protons - Mg has 12 protons, so Mg^2+ must have 10 electrons - overall charge = +12 -10 = +2 isotopes - CORRECT ANSWER-are atoms of the same element with different number of neutrons, but same number of protons - different mass number which mean there's different number of neutrons - the atomic numbers are the same. what decides the chemical properties of an element? - CORRECT ANSWER-- number and arrangement of electrons - isotopes have the same electron configuration, so they've got the same chemical properties Isotopes of an element do have slightly different... - CORRECT ANSWER-physical properties, such as different densities, rates of diffusion, etc - because physical properties tend to depend on the mass of an atom the atoms and electrons (models of atomic structure) - CORRECT ANSWER-during early years of twentieth century, physicians made great strides in understanding the structure of the atom john dalton - CORRECT ANSWER-- at start of 19th century John Dalton described atoms as solid spheres, and said that different spheres made up the different elements jj thompson (1897) - CORRECT ANSWER--discovered the electron - first sub-atomic particle to be discovered - this showed that atoms weren't solid and indivisible. - the 'solid sphere' ideas of atomic structure had to be changed - new model is known as the 'plum pudding model' - he showed that electrons were negatively charged and electrons from all elements were the same - as electrons had a negative charge, there has to be some source of positive charge inside the atom - also as electrons were lighter than whole atoms, there had to be something to account for the rest of the mass of the atom (thompson suggested that the electrons were located within the atom in circular arrays) In 1909, Ernest Rutherford - CORRECT ANSWER-- Ernest Rutherford and his team found that most of the mass and all the positive charge of the atom was in a tiny central nucleus - they fired positively charged alpha particles (helium particles) at a very thin film of gold - plum pudding model suggested that most the alpha particles would be slightly deflected by the positive 'pudding' that made up most of the atom. - most of the particles passed straight through the gold and only a small number being deflected backwards - plum pudding model cannot be right - Rutherford developed the nuclear model of the atom - in which there's a tiny positively charged nucleus surrounded by a 'cloud' of negative electrons- most of atom is empty space Niels Bohr - CORRECT ANSWER-- put forward idea that atom consisted of a tiny positive nucleus orbited by negatively- charged electrons