2432396
Descripción
Fichas por Tom Fitzgerald, actualizado hace más de 1 año
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Creado por Tom Fitzgerald
hace más de 9 años
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| Pregunta | Respuesta |
| 1.1 Atoms, elements, and compounds | - There are about 100 different elemtents of which all things are made - The periodic table list' these elements - Each element is made of one type of atom - Every element has a representation as a chemical symbol e.g. Gold: Au - In a periodic table the elements are organised in columns, called groups. Elements in the same group usually have similar properties. - Atoms have a tiny nucleus surrounded by electrons - When elements react they form together with other elements to create compounds. - A compound is formed when two or more elemnts combine together. |
| 1.2 Atomic structure | - The nucleus of an atom contain two types of particles, protons and neutrons. - Protons have a posotive charge - Neutrons have no charge - Electrons are tiny negatively charged particles, that move around the nucleus. - An atom has no overall charge because: Electron: -1 Protons: +1 Neutrons: 0 Therefore the overall charge is 0 - The atomic number is the number of protons in an atom. All atoms of the same element has the same atomic no. - mass number= protons + neutrons |
| 1.3 The arrangment of electrons in atoms | - each electron in an atom is in a shell. - Electrons with the lowest energy level in the shells nearest the nucleus. (and vise versa) - elements in the same group, have the same number of electrons in their outer shells - group 1 elements react quickly with water and oxygen - group 1 elements are all reactve, the lower you go down the group the more reactive the elements become e.g. Potassium is more reactive than Lithium - Atoms of the ureactivenoble gases (group 0) have very stable electron arrangements e.g. Krypton: 2-8-8-8-8-2 |
| 1.4 Forming bonds | - When different elements react together they form compounds - metal + non-metal -> ions are formed - metal atoms lose one or more electrons to form posotively charged ions - non metals gain electrons to form negatively charged ions - The oppositily charged ions attract each other strongly, and the compound then has ionic bonds. - The chemicle formula of a compound shows us the simplest ratio of elements in a compound. E.g. NaCl shows us that an equal number of Na atoms were used as Cl atoms. - When non-metals react their atoms share electrons and form covalent bonds. These are molecules - The chemical formula of a compound/molecule shows us the number of atoms that partook in the reaction. e.g. H20 shows us 2 hydrogens and an oxygen atom. |
| 1.5 Chemical equations | - In chemical reactions the atoms that form the reactants re-arrange themselves to form the products - In a chemical reactions atoms are not created nor are they destroyed - The number and type of atom shouldbe the same before and after the reaction. - The mass of the the reactants = mass of products - Symbol equations, when written should always be balanced. |
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