CHEM CHAPTER 2

• What are isotopes isotopes are atoms of the same element with different numbers of neutrons and different masses
• What is the relative charge and relative mass for protons, neutrons and electrons? Protons relative charge = +1 and relative mass = 1 Neutrons relative charge = 0 and relative mass = 1 Electrons relative charge = -1 and relative mass = 1/1836
• Mass n.o? Protons + Neutrons (Big n.o)
• Atomi n.o? Protons (Small n.o)
• What are Ions? Ions are atoms that have gained or lost electrons, giving them an overall positive or negative charge. CATION: Positively charged ions (lost electrons) to gain a full outer shell. ANIONS: Negatively charged ions (gained electrons) to gain a full outer shell.
• What is relative isotopic mass? The mass of an isotope of an element is compared to 1/12th of the mass of a carbon-12 atom.
• What is relative atomic mass? The weighted mean mass of an atom of an element compared to one-twelfth of the mass of a carbon-12 atom.
• What is relative molecular mass? The mean mass of a molecule compared to one-twelfth of the mass of a carbon-12 atom.
• What is Mass spectrometry? Calculates the relative atomic mass of an element given the relative abundance of all the isotopes. Used to determine the mass of a molecule or isotope present in an element by measuring mass:charge ratio
• How does mass spectrometry work? 1) A sample is placed on mass spectrometry 2) Sample is vapourised and then ionised (turns to ion by gaining/losing e-) to form positive ions. 3) Ions are accelerated Lighter ions move faster than heavier ions as they are Difficult to deflect.This separates the ions of each isotope 4) Ions are detected on a mass spectrum as a mass: charge ratio Ions hit a detector, which produces a signal.The greater the abundance, the greater the signal
• Ionic bonding? Metal + Non-metal react (transfer e-) to gain full outer shell
• Forming compounds? Compounds are created when e- transferred between atoms to gain a full outer shell. (Oppositely charged ions are attracted to each other)
• Nitrate? NO₃⁻
• Carbonate ion? CO₃²⁻
• Sulfate ion? SO₄²⁻
• Hydroxide ion? OH⁻
• Ammonia NH₄⁺
• Zinc ion? Zn2+
• Silver ion? Ag⁺
• Form a compound? 1) Write the elements: e.g. Ca ²⁺ and NO₃⁻ 2) Swap charges: e.g Ca⁻ and NO₃​²⁺ 3) Dop the charges: e.g Ca and (NO₃)​₂ 4) Combine and simplify: e.g Ca(NO₃)​₂