PHB page 237

Elemental Weapon

3-level Transmutation

A nonmagical weapon you touch becomes a magic weapon. Choose one o fthe following damage types: acid, cold, fire, lightning, or thunder. For the duration, the weapon has a +1 bonus to attack rolls and deals an extra 1d4 damage of the chosen type when it hits.
At higher levels: When you cast this spell using a spell slot of 5th or 6th level, the bonus to attack rolls increases to +2 and the extra damage increases to 2d4. When you use a spell slot of 7th level or higher, the bonus increases to +3 and the extra damage increases to 3d4.