Silver at a glance
- Atomic number
- 47
- Symbol
- Ag
- Atomic mass
- 107.87 u
- Category
- Transition metal
- Group / period
- 11 / 5
- Electron configuration
- [Kr] 4d 10 5s 1
- State at 25 °C
- Solid
- Melting point
- 961.8 °C
- Boiling point
- 2162 °C
- Density
- 10.5 g/cm³
- Electronegativity
- 1.93
- 1st ionization energy
- 731 kJ/mol
- Oxidation states
- +1
- Discovered
- Antiquity
Atomic structure
A neutral silver atom has 47 protons and 47 electrons, and its most common isotope carries about 61 neutrons. One atom weighs about 1.79 × 10⁻²⁵ kg, so a mole of silver (6.022 × 10²³ atoms) weighs 107.87 g. That nucleus holds 1.3 neutrons for every proton. Its symbol Ag comes from argentum. The electrons fill 5 shells (K 2, L 8, M 18, N 18, O 1), which gives the configuration [Kr] 4d 10 5s 1. As a d-block element, both its outer s electrons and its inner d electrons can take part in bonding, which is why it shows more than one oxidation state. Its configuration breaks the simple filling order: one electron moves so that a subshell becomes half-full or full, which is more stable. It has 2 stable isotopes: Ag-107 and Ag-109. Its most common isotope, Ag-108, has the same mass number as Pd-108 and Cd-108: isobars, nuclei of different elements with 108 nucleons each.
Physical properties
At room temperature (25 °C) silver is a solid. It melts at 961.8 °C and boils at 2162 °C, so it stays liquid across a 1200-degree range. It stays solid in a hot kitchen oven but would melt in a candle flame (about 1000 °C). Its density is 10.5 g/cm³, 10.5 times as dense as water. Its atoms have a radius of about 160 pm (Palladium next door is 140 pm). In the solid, its atoms pack into a face-centred cubic lattice.
Chemical behaviour
Its electronegativity is 1.93 on the Pauling scale. Pulling off its outermost electron takes 731 kJ/mol, less than Copper above it (746 kJ/mol). A bond between silver and chlorine would be polar covalent, with an electronegativity difference of 1.2. It releases 126 kJ/mol when it gains an extra electron. Its common oxidation states are +1, so in compounds you will usually meet it as Ag⁺. Group 11 also holds Copper, Gold and Roentgenium, which share its outer-shell pattern.
Where it comes from
It makes up 0.075 mg/kg of Earth's crust, the 68th most abundant element there. It has been known since ancient times, one of only 11 elements people used before modern chemistry.