Period 5 element other metal is not easily oxidized in air and is used to coat other metals to prevent corrosion. The firstalloy, used in large scale since 3000 BC, was bronze, an alloy of tin and copper. After 600 BC pure metallic tin was produced. Pewter, which is an alloy of 85–90% tin with the remainder commonly consisting of copper, antimony and lead, was used for tableware from the Bronze Age until the 20th century. In modern times tin is used in many alloys, most notably tin/lead soft solders, typically containing 60% or more of tin. Another large application for tin is
Distributed element filter composite structures can implement any of the filter families (Butterworth, Chebyshev, etc.) by approximating the rational transfer function of the corresponding lumped element filter. This correspondence is not exact since distributed element circuits cannot be rational and is the root reason for the divergence of lumped element and distributed element behaviour. Impedance transformers are also used in hybrid mixtures of lumped and distributed element filters (the so-called semi-lumped structures). Another very common component of distributed element filters is the stub. Over a narrow range of frequencies, a stub can be used as a capacitor or an inductor (its impedance is