Metals and Reactivity Flashcards
Describe the Group 1 alkali metals, lithium, sodium, and potassium
Relatively soft metals
Describe the Group 1 alkali metals, lithium, sodium, and potassium (decreasing melting points)
As you move down Group 1, the melting points of the alkali metals generally decrease. Lithium has the highest melting point among the group with a value of approximately 180.5 degrees Celsius (356.9 degrees Fahrenheit). Sodium has a lower melting point of around 97.8 degrees Celsius (208 degrees Fahrenheit), while potassium has an even lower melting point of about 63.5 degrees Celsius (146.3 degrees Fahrenheit). This decreasing trend is due to the weakening of metallic bonds as the size of the atoms increases down the group.
Describe the Group 1 alkali metals, lithium, sodium, and potassium (Increasing density)
The density of alkali metals increases as you move down Group 1. Lithium is the least dense metal among the group, with a density of about 0.534 grams per cubic centimeter. Sodium has a higher density of approximately 0.97 grams per cubic centimeter, and potassium is the most dense alkali metal with a density of around 0.89 grams per cubic centimeter. The increasing trend in density is primarily attributed to the increased atomic mass and size of the atoms as you go down the group.
Describe the Group 1 alkali metals, lithium, sodium, and potassium (Increasing reactivity)
The reactivity of alkali metals also increases as you move down Group 1.
Lithium is the least reactive alkali metal, while potassium is the most reactive. Alkali metals are highly reactive because they have a single electron in their outermost shell, which they readily lose to form a positive ion. As you go down the group, the outermost electron is farther from the positively charged nucleus, making it easier to remove. Therefore, the alkali metals become increasingly reactive with water, oxygen, and other substances as you progress from lithium to sodium and potassium.
Describe the transition metals
- They have high densities
- They have high melting points
- They form coloured compounds
- They often act as catalysts as elements and in compounds
Compare the general physical properties of metals and non-metals (including thermal conductivity, electrical conductivity, malleability and ductility, melting points and boiling points)
- Thermal - Metals: Metals generally have high thermal conductivity, meaning they can efficiently transfer heat. This property is due to the presence of delocalized electrons that can move freely throughout the metal structure and transfer thermal energy.
Non-metals: Non-metals, in general, have lower thermal conductivity compared to metals. They are typically poor conductors of heat and tend to have lower thermal conductivity values. - Electrical - Metals: Metals are generally good conductors of electricity. The presence of delocalized electrons allows for the efficient flow of electric current through metals. This property makes them valuable for use in electrical wiring and other electrical applications.
Non-metals: Non-metals are generally poor conductors of electricity. They lack the presence of delocalized electrons required for efficient electron flow. However, some non-metals, such as graphite, can exhibit conductivity under specific conditions. - Malleability and Ductility - Metals: Metals are typically malleable, which means they can be hammered or rolled into thin sheets without breaking. They are also ductile, meaning they can be drawn into thin wires without breaking. These properties are due to the metallic bonding and the ability of atoms to shift and rearrange under applied force.
Non-metals: Non-metals, in general, are not malleable or ductile. They tend to be brittle and break when subjected to mechanical stress, instead of undergoing plastic deformation. - Melting points and Boiling points - Metals: Metals generally have high melting and boiling points. The metallic bonds that hold the atoms together are strong, requiring significant energy input to break them and change the state of the metal.
Non-metals: Non-metals have varying melting and boiling points, but they generally have lower melting and boiling points compared to metals. Non-metallic compounds often have weaker bonds, such as covalent or molecular bonds, which require less energy to break and change their state.
Describe the general chemical properties of metals limited to their reactions with: (Dilute acid)
Metals generally react with dilute acids to form metal salts and release hydrogen gas. The reactivity of metals with dilute acids depends on the specific metal and follows a trend similar to the reactivity trend within their respective groups on the periodic table.
Describe the general chemical properties of metals limited to their reactions with: (Cold water and steam)
The reactivity of metals with cold water and steam can vary. Alkali metals and alkaline earth metals are highly reactive with cold water, while other metals may react at a slower rate. The reactions generally involve the displacement of hydrogen from water, leading to the formation of metal hydroxides and the release of hydrogen gas. When reacting with steam, metals can form metal oxides and release hydrogen gas. However, it’s important to note that not all metals react with water or steam, and noble metals tend to be unreactive in these conditions.
It’s important to note that not all metals react with cold water or steam. Some metals, particularly noble metals such as gold (Au) or platinum (Pt), are unreactive and do not undergo significant reactions with either cold water or steam.
Describe the general chemical properties of metals limited to their reactions with: (Oxygen)
Metals can react with oxygen to form metal oxides. The reactivity of metals with oxygen can vary, with alkali and alkaline earth metals being highly reactive, some metals forming protective oxide layers, and noble metals being unreactive. These reactions play a crucial role in corrosion processes and the formation of metal oxides.
Describe the uses of metals
- Aluminium - Manufacture of aircraft because of its low density
- Aluminium - Manufacture of overhead electrical cables because of its low density and good electrical conductivity
- Aluminium - Food containers because of its resistance to corrosion
- Copper - Electrical wiring because of its good electrical conductivity and ductility
Describe an alloy
A mixture of a metal with other elements
Give examples of alloys
- Brass - Mixture of copper and zinc
- Stainless steel - Mixture of iron and other elements such as chromium, nickel and carbon
Compare alloys to pure metals
They can be harder, stronger, and more useful
Describe the uses of alloys in terms of their physical properties (including stainless steel)
Stainless steel is a popular choice for cutlery, including knives, forks, and spoons. Its hardness and resistance to rusting make it an ideal material for kitchen utensils. Here’s how its physical properties contribute to its use:
Hardness: Stainless steel is a hard material, which means it can withstand use and retain its sharpness for longer periods. This hardness allows stainless steel knives to maintain their cutting edge and resist deformation or dulling, even when used on hard food items.
Resistance to Rusting: One of the most significant advantages of stainless steel is its excellent resistance to rusting or corrosion. Stainless steel contains a high proportion of chromium, which forms a thin, invisible layer of chromium oxide on its surface. This oxide layer acts as a protective barrier, preventing the underlying metal from reacting with oxygen and moisture in the air. As a result, stainless steel cutlery remains resistant to rust, even when exposed to water and humidity.
Explain in terms of structure how alloys can be harder and stronger than pure metals
When different-sized atoms are present in an alloy, they can disrupt the regular arrangement of atoms in the crystal lattice of the pure metal. This disruption of the crystal structure can lead to increased hardness and strength compared to pure metals. Essentially the layers could no longer slide over each other.
