Actually, the NHL had 7 teams prior to the 1941/42 season.In 1942, the New York Americans dropped out of the league and the NHL operated with six teams until 1967. There was no "seventh" team , as such, because the NHL added a full six teams at the same time to bring the league's number up to 12.
9
The website below gives you plenty of players who wore the #1 in the NHL. Click on the related link.
Ron Francis wore number 10 during his career in the NHL.
Guy Lafleur from the Montreal Canadiens
Paul Bibeault - Montreal Canadiens 1942-43.Neil Sheehy - Hartford Whalers 1987-88.
16 and 17. He wore 16 prior to his stint in the WHA. Upon his return to the NHL he wore number 17.
Bill Cerv wore #7 in 1951 before Mantle did.
Borje Salming wore number 21 for the Toronto Mapleleafs. However, he left the team in 1989 and his number 21 was taken by a future NHL star named Sean McKenna.
11
Michael Owen wore jersey number 7 for mancunian republic in 2010-2011.
Roughly 4-7% go straight to the NHL
QB Ron Jaworski.Jaworski wore #7 for the Eagles between 1977-1986.